RPI: Use a WiFi AP to broadcast the RPI local network

I’ve been running into some difficulty trying to figure out how to go about the project I would like to do. Here is a flow chart of my approach.

Docker Container > RPI > (via eth0) WiFi AP > Opening the local container via web-browser, probably on a phone.

So far I’ve set up the docker container on the RPI (v4 w/ 64bit debian OS), and have all of the physical connections set. I am struggling to get the RPI and the AP to communicate. I think what I’m going to need to do is have the RPI host a DHCP server, the AP as a client, and once I am connected to the AP through WiFi I am able to access the local host page, probably on the docker IP of 172.17.0.1. Is there an easier way to approach this? I honestly have never worked with any of these aspects, and have a background in aerospace engineering so this is all completely new.

I have followed this guide with a few modifications due to typos, but cannot get it to work.
https://gist.github.com/Konamiman/110adcc485b372f1aff000b4180e2e10

Does anyone have any resources/approach to do this from? I’m also struggling to search in the correct manner to procure results.