Project EV app ask for Authorization Key

[ppmt]

Hello,
I have an charger from Project EV (the APEX-7.3). It is connect via the integration to Home Assistant it works fine (I am still on v9.0.0)

One question I have for other owner is if you are using an authorization key. In the app in the ocpp setting it asks for one. Now it works without one but I am curious what improvement if any it will bring if I use a key.

I have contact Project EV about it and they told me that that key comes from the OCPP provider not from the charger.
So my question is where I find that key or how do I generate one ?