some team members unable to join on audio on MS teams

[Niyati]

How is that some team members are able to join audio via the meeting link while others can't 

[#2]

Do they use the desktop client or the web client for Teams? If they use the web application what browser do they use?

Check supported web browsers here:
https://docs.microsoft.com/en-us/microsoftteams/limits-specifications-teams#browsers

Download desktop client here:
https://teams.microsoft.com/download