Installing Teams Self-service as an app in Teams is easy - this is how.
But if you want the app as an icon in the Teams sidebar, you need to access the Teams settings at tenant level. These are changes that will affect all users on your tenant that have the app installed.
This is how.
1. With a user who has admin rights on your tenant (e.g. Global Admin), go to portal.office.com and click Admin.
2. Then click Administration and pick Teams.
3. Expand the Teams-apps and click Konfigurer politikker.
4. Click Global (standard på tværs af organisationen).
5. This displays the list of apps currently in the navigation sidebar.
Click Tilføj apps.
6. Search for the app (TDC Erhverv) and click Tilføj and then Tilføj at the bottom.
7. The app has now been added to the list just below Files.
The app icon has now been added - but please note that it may take several hours before the change is live in the application.
If the app is not pinned in the side menu (i.e. disappears when not in use), right-click on the icon and select Pin.