Hello caoimhe161,
Thank you for taking the time to post your questions to Apple Support Communities, and congratulations on your new MacBook Air. We understand that you're experiencing issues with installing Rosetta, along with signing into your Apple ID for iMessage and FaceTime, and your email account.
You mentioned needing to install Microsoft Teams. If the device is for work, and you're connected to a VPN, disconnect from that VPN and try again. Testing on a different network can help us isolate things a bit more.
The steps here can help with the issues signing into your iMessage and FaceTime account: If you can't sign in to your iMessage account or FaceTime on your Mac
If you continue to experience these same issues, let's test with your Mac in safe mode: How to use safe mode on your Mac
We look forward to hearing the results.
Cheers!