Download and install the latest Bugsee.unitypackage package and install it in your project. This should install all the necessary files in the Assets folder of your project.
Make sure the files were indeed added to your project and create a new empty object within a scene:
Select the new object and add BugseeLauncher script component to it:
Once the component is added, you will be presented with the options screen, which contains Android and iOS apps token fields. If you compile your app for the single mobile platform, you can set only corresponding app token.