@Proape 

For a smart bulb that is configured over WiFi (the other type is Bluetooth), there are two steps in the configuration process that require a WiFi connection. the first is connecting to the smart bulb WiFi, which is the step you are stuck with, and this is the step that connects your phone to the smart bulb wifi to allow the kasa app to discover the device and proceed to the next step.

In your phone's WiFi list, you should find a WiFi with a name similar to Kasa Smart Bulb XXXX. When the app prompts you to connect to the device's WiFi, go to your phone's WiFi list and manually connect to this WiFi, and then go back to the kasa app to proceed with the rest of the configuration.

Then the next step will be selecting a router WiFi to connect.

More details on this instruction about How to connect TP-Link Smart Bulb to my home network via Kasa