"that the system would warn me about read only"

Yes, I explained this. You need to treat one of the computers as a server, and you install programs for server installation, not stand-alone, and then no one uses the NAS directly. You have not got a Managed sharing installation.

Look at this image:

https://www.lifewire.com/thmb/u6dx1LLBgF5JS0msJ1CshQqRBq0=/1500x0/filters:no_upscale():max_bytes(150...

You did the Red part, but you wanted the Blue part.