First mount your NAS NFS share to a local empty directory on your Linux mint PC.
After that you should be able to access the NFS share in than directory.
Then just rclone into that directory in the same way as using rclone in any other directory.
How to mount NFS share:
You may need to install the needed NFS packages in mint (the guide is for Arch Linux but I could not find any good guides for mint). I guess ubuntu is identical to mint so maybe you can search for ubuntu nfs mount.
Edit: You can use the ip address of your NAS as server name or add the NAS name and ip in your /etc/hosts file if you want an easier name to remember.