Introduction
The next step is to upload the ZIP file, including the icons, into the Microsoft Teams admin center.
Instructions
Upload the zipfile
Go to the Microsoft Teams admin center.
Go to Teams apps.
Select Manage apps.
Click Upload to upload the ZIP file (double-check if it's a .zip).
To upload a new version of the manifest, simply click Upload file and upload the new zipfile.
Proceed to step 4.