Guests have similar capabilities to team members and can participate in meetings, chats, and work on documents.
In a team, select More options>Add member.
Enter the guest's email. You can add as many guests as you need.
If needed, it's best to change their display name now.
When ready, select Add and guests will be sent an email invitation they need to accept to begin.
A guest will have the label "Guest" attached to their name in Microsoft Teams. You can also check the top of any channel to see how many guests are in it.
To share files, use the Files tab and folders since document links may not work with guests.