MTR-W testing

[SlaydeZero]

I am the MS Teams Admin for my company. I am trying to test out the external meeting invites which is enabled on all 1700 MTR devices, but stopped working. To test it out, I created an account and scheduled a meeting and sent the invites to the device accounts in my AV lab. Both my device do not show a meeting. I was looking and read that zoom doesn't send invites? which is odd...

I am sure I am doing this wrong somehow. I know I also created an ICS file in my outlook and forwarded them to my devices, which the meetings did show up that way. But I could not join my devices to the meeting in that fashion. 

Kinda silly being a high level teams admin but have no exposure to Zoom. Can someone tell me what I am missing so I can address this?
Thanks!