`Google' does not exist in the current context

I've been stuck on this for weeks, Trying to implement a different ad service (Appodeal). Every time it says it builds correctly, but when looking at the log it's filled with errors all over and when downloading and installing on my phone (Android) and running it, it doesn't do anything. While when running on the editor it just says that the ads aren't loaded and continues on. Nothing in the code is stopping it.

I need this to work for Android before I move over to iPhone. Please someone help.