Short answer
Install the eSIM from inside the app, then confirm it was added in your Android phone settings.
Before you start
Make sure your Android phone supports eSIM.
Make sure the device is unlocked.
Use stable Wi-Fi.
Install the latest Android update if available.
Steps
Open the app.
Open your purchased plan.
Tap Install eSIM.
Follow the Android system prompts.
Open phone settings and confirm the eSIM was added.
Android menu names vary by brand. Look for:
Settings → Connections / Network & Internet → SIM Manager / SIMs / Mobile Network.
After installation
Make sure the eSIM line is turned ON.
Choose it for Mobile Data when you want to use it.
Turn Roaming ON for the eSIM when using data abroad.
If installation fails
Check whether the eSIM already appears in phone settings. If it does, do not try to install it again; contact support with a screenshot of the eSIM list and the error.