Hi
My name is Daniel. I am an Independent Advisor and consumer of Microsoft products, I will be more than happy to help you.
There are a few things you need to check if you don't see the join meeting button. Here's I give you checklists, please visit one by one.
* There are multiple ways to join a meeting, could you please double-check whether you are unable to find the join button in another medium such as email, MS Team mobile app etc. Please refer to this article:
https://support.microsoft.com/en-us/office/join...
* There's a chance the admin has disabled the meeting policy as explained in this article:
https://answers.microsoft.com/en-us/msteams/for...
* Sometimes this issue can be an intermittent issue. If you are experiencing the issue on the computer doesn't mean you will experience this issue on a mobile device and vice versa as explained in this article:
https://answers.microsoft.com/en-us/msoffice/fo...
* Please go to your computer then open your chrome or edge browser as recommended browsers and see whether you are experiencing the same problem when using MS Teams online
https://teams.microsoft.com
* Some users are able to join the meeting if they copy the invitation link from your email into the web browser on their computer. Please keep in mind as of this moment only Chrome or Edge browser are supported.
* If the problem still persists I would recommend asking the owner of the Team/Channel to remove you from the Team/Channel then re-adding you again and see if that resolves the problem.
Kind Regards
