improve "open in app" page

lang/main-de.json

         "description": "Nichts passiert? Wir haben versucht, die Konferenz in {{app}} zu öffnen. Versuchen Sie es erneut oder treten Sie der Konferenz in {{app}} im Web bei.",
         "descriptionWithoutWeb": "Ist nichts passiert? Wir haben versucht, Ihre Besprechung in der „{{app}}“-Desktop-App zu starten.",
         "downloadApp": "App herunterladen",
+        "ifDoNotHaveApp": "Wenn Sie die App noch nicht haben:",
+        "ifHaveApp": "Wenn Sie die App bereits haben:",
+        "joinInApp": "An dem Meeting teilnehmen mit der App",
         "launchWebButton": "Im Web öffnen",
-        "openApp": "In der App fortfahren",
         "title": "Die Konferenz wird in {{app}} geöffnet...",
         "tryAgainButton": "Erneut mit der nativen Applikation versuchen"
     },

lang/main-enGB.json

         "description": "Nothing happened? We tried launching your meeting in the {{app}} desktop app. Try again or launch it in the {{app}} web app.",
         "descriptionWithoutWeb": "",
         "downloadApp": "Download the app",
+        "ifDoNotHaveApp": "If you don't have the app yet:",
+        "ifHaveApp": "If you already have the app:",
+        "joinInApp": "Join this meeting using the app",
         "launchWebButton": "Launch in web",
-        "openApp": "Continue to the app",
         "title": "Launching your meeting in {{app}}…",
         "tryAgainButton": "Try again in desktop"
     },

lang/main-ja.json

         "description": "何も起こりませんでしたか？ {{app}} デスクトップアプリで会議を開始しようとしました。 再度試してみるか、{{app}} Webアプリで起動してください。",
         "descriptionWithoutWeb": "",
         "downloadApp": "アプリをダウンロードする",
+        "ifDoNotHaveApp": "まだアプリを持っていない場合は、",
+        "ifHaveApp": "すでにアプリを持っている場合は、",
+        "joinInApp": "アプリで会議に参加する",
         "launchWebButton": "Webで起動する",
-        "openApp": "アプリで続く",
         "title": "{{app}} で会議を開始する…",
         "tryAgainButton": "デスクトップでもう一度お試しください"
     },

lang/main-nl.json

         "appNotInstalled": "U hebt de mobiele app {{app}} nodig om op uw telefoon aan deze vergadering deel te nemen.",
         "description": "Gebeurt er niets? Er is geprobeerd uw vergadering te starten in de desktop-app {{app}}. Probeer het opnieuw of start de vergadering in de web-app {{app}}.",
         "descriptionWithoutWeb": "",
-        "downloadApp": "De app downloaden",
+        "downloadApp": "Download de app",
+        "ifDoNotHaveApp": "Als u de app nog niet heeft:",
+        "ifHaveApp": "Als u de app al heeft:",
+        "joinInApp": "Neem deel aan de vergadering met de app",
         "launchWebButton": "Starten via web",
-        "openApp": "Doorgaan naar de app",
         "title": "Uw vergadering wordt gestart in {{app}}…",
         "tryAgainButton": "Opnieuw proberen op desktop"
     },

lang/main.json

         "description": "Nothing happened? We tried launching your meeting in the {{app}} desktop app. Try again or launch it in the {{app}} web app.",
         "descriptionWithoutWeb": "Nothing happened? We tried launching your meeting in the {{app}} desktop app.",
         "downloadApp": "Download the app",
+        "ifDoNotHaveApp": "If you don't have the app yet:",
+        "ifHaveApp": "If you already have the app:",
+        "joinInApp": "Join this meeting using the app",
         "launchWebButton": "Launch in web",
-        "openApp": "Continue to the app",
         "title": "Launching your meeting in {{app}}...",
         "tryAgainButton": "Try again in desktop"
     },

react/features/deep-linking/components/DeepLinkingMobilePage.web.js

                     <p className = { `${_SNS}__text` }>
                         { t(`${_TNS}.appNotInstalled`, { app: NATIVE_APP_NAME }) }
                     </p>
+                    <p className = { `${_SNS}__text` }>
+                        { t(`${_TNS}.ifHaveApp`) }
+                    </p>
                     <a
                         { ...onOpenLinkProperties }
-                        href = { this._generateDownloadURL() }
-                        onClick = { this._onDownloadApp }
+                        className = { `${_SNS}__href` }
+                        href = { generateDeepLinkingURL() }
+                        onClick = { this._onOpenApp }
                         target = '_top'>
-                        <button className = { downloadButtonClassName }>
-                            { t(`${_TNS}.downloadApp`) }
+                        <button className = { `${_SNS}__button ${_SNS}__button_primary` }>
+                            { t(`${_TNS}.joinInApp`) }
                         </button>
                     </a>
+                    <p className = { `${_SNS}__text` }>
+                        { t(`${_TNS}.ifDoNotHaveApp`) }
+                    </p>
                     <a
                         { ...onOpenLinkProperties }
-                        className = { `${_SNS}__href` }
-                        href = { generateDeepLinkingURL() }
-                        onClick = { this._onOpenApp }
+                        href = { this._generateDownloadURL() }
+                        onClick = { this._onDownloadApp }
                         target = '_top'>
-                        {/* <button className = { `${_SNS}__button` }> */}
-                        { t(`${_TNS}.openApp`) }
-                        {/* </button> */}
+                        <button className = { downloadButtonClassName }>
+                            { t(`${_TNS}.downloadApp`) }
+                        </button>
                     </a>
                     { renderPromotionalFooter() }
                     <DialInSummary