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.
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
Select Add. Guests will receive a welcome email invitation that includes some information about joining Teams.