Based on your responses above, it appears you may need to better understand the functions of different types of VPN and networking.

NordVPN is a pubic VPN that provides another layer of protection for your internet traffic by tunneling and encryption to prevent packet sniffing and to anonymize the communication between your computer and the destination.

Communication within your LAN/WAN is presumed to be safe behind the firewall that should have been set up on your router as well as individual computers.  Communication between the router and each connected device should also have been encrypted with at least WPA2-AES, ideally with the Enterprise variant.

If you need to VPN into your network from outside, you will need to set up a private VPN, which NordVPN is not.  My only experience is with CISCO and only as a user - that is probably not an economical option for a small office though.  FWIW, Windows also has a built-in function that allows the PC to work as a VPN server.  There are other alternatives but I am not familiar with them and because you need to open certain ports through your firewall, it's definitely something you would want a professional to set up for you.

In case you need access to your network from the outside, remote desktop could be a viable option.  Unlike private VPN where you may have a server that could function as a virtual machine, you will need a physical machine for each connection.  My understanding is that private VPN would allow more access control than just remote desktop.  In terms of security, you would definitely want to make sure you layer as many levels of protection as you can by practicing good password management, turning on 2FA, and using pubic VPN at the very least.  One of the software I have used, which is quite popular, is TeamViewer.  LogMeIn is one other example although I haven't used it myself.

Given the amount of confidential information hosted on your network, you would be well advised to weigh your options and ensure you have the necessary safeguard in place.