Adding a Guest User in Teams.

Guests must have a Microsoft 365 work or school account. If the guest doesn’t yet have a Microsoft account associated with their email address, they will be directed to create one for free.

To add a guest to your team in Teams:

1. Select Teams  and go to the team in your team list.

2. Select More options  > Add member.
   
   

3. Enter the guest's email address. Anyone with a business or consumer email account, such as Outlook, Gmail, or others, can join your team as a guest.

   Note: If you receive a "We didn't find any matches" error while trying to add a guest, your organization doesn't allow guests. 

4. Add your guest's name. Select Edit guest information  and type a friendly name for them. Be sure to take the time to do this now—you’ll need the help of an IT admin to do it later.
   
   

5.  Click Add. Guests will receive a welcome email invitation that includes some information about joining Teams and what the guest experience is like. 
   
   Now that all that's done, the next thing you're going to do is set guest permissions.