Connection from the plug to the smartphone is via Bluetooth. After connecting, the plug recognises Wi-Fi networks and displays them in the app. Then select your own network in the app and enter your password. The plug then connects to the network.
The W-Lan function makes sense if the plug is to be used with e.g. Google Home. It then also serves as a bridge for EgloConnect lamps that do not have their own wifi function.
I have not found a way to operate it without wifi.

AroserHardy's answer is correct.
But the thing also runs autonomously with the programmes once activated and can be reprogrammed via Bluetooth at any time.