Google Cast - Android Build fails

Hello Community,

I am trying to develop a game for mobile devices. This game requires the functionality of streaming my game to an google chromecast. I found the Google Cast Plugin on the UnityAssetstore Link to the store page but everytime I tried to build for android, I got the following error three error messages:

First Error

Second, Third and Fourth Error
.
Additional Plugins installed and required by Google Cast: + Android/appcompat + Android/google-play-services_lib + mediarouter
.
I really hope somebody of you can help me out on this.
.
I thank you guys in advance!