script generates invalid key?

Hello. Short version: I ran your script, it generated a .conf file, but I cannot use this with my mac wireguard client:

I'm not sure how to proceed from here.

Long version: I'm attempting to use wireguard to get around a mysterious bug that disallows routing between my VM and host (Macbook M2 host, Linux arm guest as the router). With previous versions of everything I could do this via ip masquerade which was ideal as it was fast and hardly used any CPU (no encryption, no tunneling, etc.) Now, due to a bug that neither Apple nor Parallels want to admit exists let alone address, this nice solution no longer works. I can get other VMs to use the linux router, but not the host OS.

Anyway, my current hald-assed solution is to use ssh tunneling which hardly works and also has the side effect of bypassing my (mac-side) firewall. Not good even under ideal conditions. I tried wireguard as an alternative to see if it would work any better but got the above error.