Hi, Sorry you’re dealing with this. Since this started right after migrating to the new device, and you’re using New Outlook for Mac. Please try these steps, verify the account works in webmail first, then in Outlook, remove and re-add the account; if Outlook still hangs, use Help > Troubleshooting Information to clear cache or reset the Outlook profile, then test again.
You can also try the steps available here:
https://support.microsoft.com/en-us/office/i-can-t-send-or-receive-messages-with-outlook-for-mac-57c6d42c-3a4e-4f93-914a-212efe650a04