Hello,
I have the same problem as @edward.buchholz, I think.
I purchased the plug in and the initialization set up worked (id,user,code) but when I try to Sign in/up with apple an 400 error appears. I precisely followed the instructions on https://docs.zeroqode.com/plugins/sign-in-with-apple-plugin but I have got at each try the same issue. I try with different Key ID properly generated.
@edward.buchholz Did you manage to solve your problem ?
Thank you in advance for any advice !
Thibaut