But at this point I now need a copy on the server so a couple users can use it through RDP.I had a feeling this may come into play. I'm assuming (and correct me if I'm wrong) that the server is acting both as a file server and RDP server. If my assumption is correct, that's very disturbing from a security viewpoint, and I'm recommend separating the RDP server (putting into play an additional VM assuming that's an available option) from the file server.
https://community.intuit.com/articles/1502150-error-h101-h202-h303-or-h505-when-opening-your-company-file
You can find manual how to manually open ports in Windows server firewall to let clients work in multiuser mode.