You can use this node to load the Interstitial Ad. You can then use the Show Interstitial Ad node to show the ad.
Note: You need to also hook up the appropriate IDs and APIs for Android.
Here is another thread about the subject which is still relevant.
I also suggest looking at this resouce for setting up a project for Android: Setting Up Android SDK and NDK for Unreal | Unreal Engine 4.27 Documentation