I have an old TP-Link AC1200 EAP225 Outdoor Access Point hanging outside

I want to connect it as a mesh unit in my new Deco XE75 Mesh network

However, my Deco app doesn't recognize the EAP225 as a Deco unit, and the Omada app is so old/advanced I can't seem to figure out how to do it

Is it even possible?

As a temporary fix, I simply renamed my EAP225 Wifi SSID to the same name/password as my Deco system, and at least my devices seem to connect and hop on/off just fine

The problem is that inside my Deco app, the EAP225 shows up as a connected client to my Deco unit (they are connected by UTP cable) and not as part of the mesh.

Any advice?