The dialog pops up to let you use the virtual keyboard properly in a way that works for any localization by using a native input textbox. We do this on both Android and iOS.
As for ads, did you set up an AdMob account associated with your package and add the adunit id’s in the Android project settings?
To make text box work normally would require one of two solutions; 1) implement it yourself by creating your own virtual keyboard and dealing with coverage issues like console applications do, or 2) try to put a native text box over the area in Java.
As for the ads, try looking for any debug messages in the logcat.
Is there any way I could get some help with either method, I’ve been looking into FSlateApplication::ShowVirtualKeyboard but I have no idea how to implement it.
FSlateApplication::ShowVirtualKeyboard for Android uses a native dialog to get text. It calls AndroidThunkCpp_ShowVirtualKeyboardInput in AndroidJNI.cpp which calls into GameActivity.java (AndroidThunkJava_ShowVirtualKeyboardInput). The Java side calls back to Java_com_epicgames_ue4_GameActivity_nativeVirtualKeyboardResult with the results.