Official LevelPlay FAQ

Ads don't work while testing in the Unity Editor.

Unfortunately trying to run in editor will result in unsupported platform errors for the moment.

We may include editor testing support to LevelPlay in the future, but for now you will have to do all testing on a mobile device.

I can't get ads to show on my mobile device.

This can be the result of many different things. Please review this troubleshooting guide for assistance:
https://developers.is.com/ironsource-mobile/unity/troubleshooting-dont-see-ads-app/

I got a message saying my account was not approved. How can I use LevelPlay mediation?

You can start monetizing your app through LevelPlay mediation right away. The message you received about your account was only relevant to the ironSource Network - not Unity LevelPlay.