There are 2 ways to add guest users to a Team meeting
Before a Meeting:
To schedule a meeting with Guests, open the calendar tab of Teams and navigate to the “New Meeting” button. Type in the email of the users you want to invite and click to add them to the invites list.
The invited guest will receive an email to join the teams meeting.
Once in the meeting users who are not part of the organization will “wait” in a virtual lobby and someone in the meeting will have to let them join.
During a Meeting:
Click on the “Show Participants” button in Teams (will be next to the end call button). A side bar will appear on the right hand side with a list of meeting participants as well as a search bar to add new participants. You can either type in the name of the individual to add them or send them a link.
If the person you are trying to add is not a part of the organization you will need to send them a link. To do this click the link button (the one the red arrow is pointing to) and a link will be copied to your clipboard. You can then go to your email and send an email with the link pasted in to invite them to the meeting.