Todd,
Your network at the main office that connect to a switch which connects them to a server. Well, OptiPlex. There is a database on the server. Each client computer connects to the database via the switch, but the user is using AC which is installed on their machine. They are NOT using AC on the server, e.g. all clients actually using the AC program on the server as that is not possible.
Now, one of your client computers should be a terminal server. It will have any application you wish to use such as Word, AC, whatever. It is connected to the database of the server. No one ever uses the terminal server. THE TERMINAL SERVER IS ONLY THERE FOR CONNECTIONS FROM YOUR REMOTE OFFICE. Any application on the TS can be used by as many users from your remote office as you'd like with the proper setup and licenses. You would remote using RDP which is VERY secure and very fast. Now, I say computers from your remote office, but it could be a smartphone, a tablet, a laptop in Japan. All users connect to the same app.
