What mailbox features are required to ‘Send an email from a shared mailbox’ in Power Automate?

I am preparing an I.T. request to create a new Shared Mailbox so that we can send automated emails via Power Automate, specifically using the Send an email from a shared mailbox (V2) connector.

I want to make sure that I provide all necessary details in the request about the ‘type’ of shared mailbox that needs to be setup, as well as any necessary configuration details.

The reason I want to provide these details is that our current Shared Mailbox doesn’t provide this functionality, I am not entirely sure why – details are pasted at the bottom of this post for context.

I.T. have already said they cannot enable this functionality on the current Shared Mailbox because it is out of their scope of support, however I have suggested that a new shared mailbox may have this functionality enabled by default, so they are happy to create a new shared mailbox if that is the case.

Research

There is some information here:

Known Issues and Limitations

which says:

To use this integration, you will need access to an O365 mailbox that has the REST API enabled.

Are these the only requirements?

Is REST API enabled on new O365 mailboxes by default?

If not, is it a trivial process to enable this and where are the instructions?

Question

What mailbox features are required to ‘send from Shared Mailbox’ in Power Automate?

Context

Our current Shared Mailbox ‘Send an email from a shared mailbox (V2)’ errors

REST API is not yet supported for this mailbox.
This error can occur for sandbox (test) accounts or for accounts that are on a dedicated (on-premise) mail server.

Possible Solutions

Summary: Mailbox needs to be migrated
https://docs.microsoft.com/en-us/exchange/troubleshoot/user-and-shared-mailboxes/rest-api-is-not-yet-supported-for-this-mailbox-error

Summary: Correct license needs to be added
https://powerusers.microsoft.com/t5/Building-Flows/REST-API-is-not-yet-supported-for-this-mailbox/td-p/3452

Related reading:
https://docs.microsoft.com/en-us/connectors/office365/#issues-with-a-shared-mailbox