I believe that I setup my APIgility correctly.
I watched the tutorials and did some reading, and it’s fairly simple to setup.
I added the authentication (oauth).
My oauth2 route is correct.
I believe that my MySQL tables are correct (found the create statements in a tutorial).
The authentication type is set to oauth2 in my API.
At this stage in the code above, I haven’t reached a method, but I checked that too: authorization is setup, headers are setup.
I’ve been through everything on the APIgility side and can’t see anything incorrect.
Not familiar with FMP, so I don’t think that I’m using that.
Thanks for your help so far 
It is appreciated.