To summarize the most important steps:
Port UDP 1812/1813 (that you have configured on the SSID) have to be allowed all the way to the RADIUS server
The shared secret has to match on the AP and the RADIUS server
After that, you should have at least a log entry in your server when users connect. For me, the test function in the SSID config was never reliable. Try to connect a client and look at the server logs.
If you found this post helpful, please give it Kudos. If my answer solves your problem, please click Accept as Solution so others can benefit from it.