Android Studio App Website Login+Button Click

what can I use for Website Login + Button click on sub site for Android App in Android Studio? For login I used JSoup and it works, but I didn't find anything to click a button. I have to been logged in for that click.

What I found...
HTMLUnit < not for Android App?
Selenium < not for Android App?
Appium < I didnt get it installed very complicated..

Edit: Is there no other solution to do this simple thing? I didn't get it working htmlunit-android

Have started to make HtmlUnit working on Android - see https://github.com/HtmlUnit/htmlunit-android.

There is only a SNAPSHOT build so far but a release might be available soon. Any help e.g. testing new builds is welcome.

https://github.com/HtmlUnit/htmlunit/issues/133