Your installation settings let you know the Theme that your app is installed on, and the Bundle type is use on your store.
Within Bundle Builder, go to Settings.
Under Installation > Theme, you can check which theme the app is installed on.
To do this, simply click Check.
If you have not completed Multiple SKU Bundle Installation, you will only be able to use Single SKU Bundles.
To learn how to complete Multiple SKU Bundle Installation, please read our guide.