The team Id is a globally unique identifier that represents a Microsoft Teams group. In some rare circumstances you may require this id. To get this identifier you can follow the steps below:
Open Team Forms in your preferred web browser by navigating to https://web.teamforms.app/
On the side bar select the team you wish to find the Id for
The URL in the address bar will follow the format below and containing the team Id
https://web.teamforms.app/teams/{team_id}/forms