First of all you need to install the WatchMaker app in your phone, buying the PREMIUM account, just ONE payment <10$ (you don’t need any weekly/monthly/annual or VIP subscription) and also install the WatchMaker app in your watch (through the Google Play store app)
This video is very helpful:
To send watchfaces from the phone to the watch, you need WiFi on the watch, so it’s better to have it on the charger, or at least disconnected from the phone bluetooth (just switch off bluetooth on the phone, and that way the watch is also forced to connect to WiFi)