To access a shared mailbox on a mobile device, please follow these steps.
1. Make sure you are signed into your
primary account in Outlook on your Android device.
5. If you have multiple accounts on your Outlook Mobile,
make sure you select the account that has the permission to access the shared
mailbox you require.

After the setup process has been completed, the shared mailbox will be displayed in your account list in Outlook.
To remove a shared mailbox, go to Settings > Accounts. Then tap the shared mailbox you want to remove and select Delete Account.