Error Notification: Email login is disabled. What to do?

Hi, I have a very weird issue. I am a personal assistant. When I try to login to a zoom account of my boss, it works. However, if I try to start any of the meetings, the application gives me the error note: Your email sign in is disabled. 

I can only press 'Ok'. 

When I try to login from the app, it gives me only the option of Apple login, Google login, or SSN. Where can i login with regular email user and password for this account for the desktop app on MacBook?

Please help