bronto346 wrote: ↑Today, 08:33
F7 doesn't seem to copy anything. Is there an alternative on a Mac to copy paths?

You are pressing the F7 key and not the

key? If you're using a macOS laptop then you may need to hold the
Function modifier to actually press the
F7 key
(see How to use the function keys on your Mac) because macOS uses the F key row for media controls unless configured otherwise.

You can also use
keyboard copy & paste (press Command-C on macOS) after selecting a file item to copy & paste a complete file path from the
Original Files list.
bronto346 wrote: ↑Today, 08:39
I'd still like to work out how to fix the permissions on the external disk, because transferring to and from the laptop adds a lot of time and I do have limited space on the laptop.

What file system are you using for your external drive? exFAT? APFS?

You can usually set permissions via Finder. I'd use Google
(you will find many results; some of which will be useful; some of which will not be useful) to get some ideas and try a few things. Please let us know if you find a solution and what ended up working for you. As a last resort, you can always format / delete / reset the entire drive, but you'd have to move your files elsewhere while doing so.