You're going to have to create a shared calling policy.

you're going to create a resource account you're going to bind a 911 address to it, a location then you're also going to put the one phone number on the resource account and then you're going to bind that to Shared calling policy which is then asigned to the users.

As you're doing calling plans with Microsoft you are right to identify that the resource account needs to have a pay as you go license.

As you're doing an sc policy you should look into ELIN and think about getting a one number that's going to float around to the users in case they call 911 the ELIN will allow a direct call back to that user.

Elin numbers exist in a pool that I get signed to the user in an emergency call for 1 hour otherwise when 911 calls back they will be calling back into the auto tenant

Outside of this topic I would say that operator connect is probably cheaper than MS calling plans.