Setting up new back up on outboard nas

i am having a similar issue. I am using a QNAP and have a USB drive plugged straight into the QNAP and that backup works. I had set up another backup to another NAS which prudently stopped working. I deleted that back up path and tried to add it back but I keep getting a couple of different error messages- like Can’t find path or othe rsimilar things. The add function does not display a normal set of dialog boxes where I could drill down to the folder i want to use for backup on the NAS. I looked at the Roon instructions which say to go to explorer and then cut and paste the path into Roon but that did not work either. Any suggestions?