Note that I have snipped out your first 2 screenshots because you are showing your client secret. This is secret for a reason. You may need to see what can be done to regenerate it.
I could not find where that is set in XF, so, I created new credentials, and made sure the URL was http:// not https://, and it worked nicely! Thank you for correcting that error for me, Liam!!
As for your concern Mike, I had to create a new ID/credentials/secret ID anyway, so there was no harm showing it, but thanks for your concern!