IMPORTANT: The only way, at this time, to add a shared mailbox to a mobile device (phone/tablet) is using the Microsoft Outlook app and adding the user's primary mailbox that has been granted access to the shared mailbox.
For example, Jane Doe has a primary email of [email protected] access to a shared mailbox of [email protected]. John must install the Outlook app on her phone first, then add the shared mailbox.
Note: Each mailbox added will require a separate management approval.
Outlook for iOS (Apple iPhone): https://apps.apple.com/us/app/microsoft-outlook/id951937596
Outlook for Android (Google Phone): https://play.google.com/store/apps/details?id=com.microsoft.office.outlook&hl=en_US&gl=US&pli=1
Steps (images from an iPhone, very similar on Android)
1. iPhone - Select the user icon in the top left
Android - Select the mail icon just below your user icon in the top left
2. iPhone Click Add Mailbox
Android - Skip to 3
3. iPhone/Android - Click Add a shared mailbox, enter the email address and if you have access to the mailbox it will add.
