How do I transfer a Photos library from a NAS to my new macbook pro?

I have a new MacBook PRo. Before giving up the old one, I made a backup with Time Machine on a QNAP NAS.

I can see the backup, and I can access it through the finder. I am trying to transfer the photos library to my new computer. The transfer works for a while, but then I get an error message that the transfer won't work (error code -50).

The library is large (40 GB) and I have been able to successfully complete the transfer of smaller files. S

o my suspicion is that the connection between the NAS and the computer is just twitchy and so it is cutting out. Is that likely? Should I try to connect my computer to the NAS with an ethernet cable to establish a more secure, stable connection?

But I would also like to know if there are other, deeper concerns I should have. For example, can a computer only have one Photos library file on it at a time? I have a new user name on my new Macbook. Could that be blocking it? My work administrators have also restricted my access somewhat to my new computer, but I am an admin on this one. Could that be causing a problem?

Thank you.

Simon