Install this package using Unity's package manager:
Open Window > Package Manager
Click on the +-Button
Select Add package from git URL...
And paste this URL: https://github.com/WonderzGmbH/Mediabox-UnityClient.git?path=/Assets/Plugins/Mediabox
You should be able to see Wonderz GmbH's Wunderbox Unity SDK in the Package Manager. Select Download and Import to import the package into your project.
For a Quick Start, import the Sample Files using the Package Manager and confirm the dialogues. You should see the Game Definition Hub, Wunderbox Unity SDK's central Editor Window to configure your games for exporting and uploading (If not, open it manually using Mediabox > Game Definition Hub). And you'll be one click on Start Play Mode away to test GameB, one of the two "Games" included in the Samples, in Simulation Mode in the Unity Editor.
Congratulations on coming this far! Your next steps should be to click yourself through the imported Sample Scripts, have a look at the Game Definition Hub and try to use Build All to export your games in order to upload them to Wunderbox. Next, you can use Mediabox > Build Game to build your Unity Client and integrate it into your Mediabox-Client-Application. The Wunderbox Unity SDK will do all the work of communicating with the Wunderbox Client integrated in your native environment according to Wunderbox' Native API.