How to run a REST web service via wordpress hosted on apache wamp server for iOS front end

I am essentially trying to figure out how to persist user data from iOS on an apache wamp server which is hosting a wordpress website with a mySQL database (which is in the name wamp, but just being thorough). I have unsuccessfully attempted to add a php script to the www directory in the hopes that I may simply preform a URL request on my frontend via:

When preforming the URL request through a web browser I get this:

Now I must say that I primarily work with iOS and these backend services are completely new to me. This likely has to do with my lack of experience with php, mySQL, apache, wordpress etc.., so feel free to completely school me.

I am aware that this question may have a breadth of answers, so even something that (a link or other SO question could do etc...) presents itself as a general guide as to how to do this would be great, if my approach is completely incorrect that is.

source https://stackoverflow.com/questions/67876789/how-to-run-a-rest-web-service-via-wordpress-hosted-on-apache-wamp-server-for-ios