When setting up the Fritz SDK, you should have created a new iOS or Android application with the webapp and specified a package identifer. This identifier must match the bundle id (on iOS) and applicationID (on Android) that you build your project with. Typically in an Android project, this is set in the app/build.gradle file under android > defaultConfig > applicationId.
If you’re unsure which package id you entered into Fritz, you can find it by logging into the webapp, selecting Project Settings from the left navigation menu, and inspecting the Package Name column. If there is an error in your package name, you can delete your app with the drop down menu on the right and create a new one.