the same problem happened to me in a different context, i tried to use ebook2audiobook which also needs the same gardio file, and i got the same error like you. what helped me, was to rename the file to EXACTLY this name WITHOUT exe

frpc_windows_amd64_v0.3

do NOT add dot (.) and also do not add exe (.EXE) and then i tried a few more times and it managed to connect to the server (a link which will expire in 72 hours).