Thanks for your reply, @malvika.ite! Can you try adding type=zak as a param value instead of including it in the request body? (i.e https://api.zoom.us/v2/users/yourzoomemail.com/token?type=zak)
Then append that value to the URL like so :
https://domain.zoom.us/s/meetingNumber?zak={{ZAK token returned via Get a User Token Res}}
To rule out a caching issue, please try to join using a private browser. Let me know if this helps.
Best,
Donte