Policies and Security for the Teams App
Refer to the Microsoft site for full information, but the steps are outlined below.
Users in your organization will automatically get the global policy unless you create and assign a custom policy.
Sign into Office365 as a Teams Administrator.
Go to the Microsoft Teams admin center. The URL is admin.teams.microsoft.com/dashboard
Go to Teams Apps-> Setup Policies.
Click Add.
Enter a name and description for the policy.
Turn on or turn off Upload custom apps, depending on whether you want to let users upload custom apps to Teams. You won't be able to change this setting if Allow third-party apps is turned off in org-wide app settings.
Turn on or turn off Allow user pinning, depending on whether you want to let users personalize their app bar by pinning apps to it.
To install apps for users (in preview), do the following:
Under Installed Apps, click Add Apps.
In the Add Installed Apps pane, search for the apps you want to automatically install for users when they start Teams. You can also filter apps by app permission policy.
When you've chosen your list of apps, click Add.
To pin apps, do the following:
Under Pinned apps, click Add apps.
In the Add Pinned Apps pane, search for the apps you want to add, and then click Add. You can also filter apps by app permission policy.
When you've chosen your list of apps to pin, click Add.
Arrange the apps in the order that you want them to appear in Teams
Click Save.