I think the software center only shows certain programs you can downloaded. since you side loaded it it will show up else where. I would login and you will see the custom options on servers to connect to/ protocols etc. I don't use Eddie since I use a router, but I am familiar enough from reading the forums here
for wireguard app. login to your airvpn account go to client > config generator > check wireguard and your options. then import them into the app. then you just login with your airvpn account.