How to Join a Group /Team in MS Teams

Find and join a team in Microsoft Teams

On the left side of the app, select Teams . ...
Select Join team .
In the Type to search box, type the name or topic of the team.
Point to the team tile to reveal and select Join team.

Teams basically has two components, groups and meetings. You join both in order to attend a session. (Teams differs from Zoom in this respect.)

First, you join a Teams group. This is simply an area online within the Teams platform. You can join a group at any time. It is not a live session. A group might have some resources or a few text conversations but for the most part, nothing much happens in groups until a ‘meeting’ starts. So…
Second, you join a ‘meeting‘ within a group when the meeting starts. You will not get a notification that a meeting is happening. You need to remember to visit the group you joined earlier and look out for a meeting taking place at the scheduled time. You then select JOIN and you’ll join the live session. Simples!

If you are unable to join.

1. The code or link may have expired or been used by someone else.

2. Make sure that you have the latest version of Teams installed. If you're using an older version of Teams, you may not be able to join the team.

3. Contact the team owner.

Note: If a team owner hasn't enabled discoverability for their private team, you won't be able to find it by using search.