I have a similar issue than OmekaS + Scripto topic.
I just installed mediawiki 1.35.1 and I cannot connect it with Scripto (last release, I also tested master). I am runing Omeka S 3.0.1.
It works with this url from wikipedia: https://test.wikipedia.org/w/api.php
but not with mine (with is http only). I can access mediawiki api when visiting the …/api.ph url.
Is there some settings inside mediawiki to make it work with scripto?