Self Hosted PHP API Will Not Connect

If I select HTTP API and enter my url (https://matomo.domainname.com) it connects fine. I’m using the “use proxy script” option because I don’t want the login url listed in the code. This plugin seems to be the only way I have found to do it.

However, I cannot get the PHP API to connect and I don’t know why. The server path is /home/matomo/htdocs/matomo.domainname.com/

All the folders/files are in that directory. This plugin is in the usual place under my main domain.

I have tried every server path variation I can think of to no avail. Even created a separate auth token.

I can’t any documentation about using that feature, so I’m not sure what file it’s looking for. Is there something I’m missing?