Google Play - App Bundle Distribution: No Google Play Store Key

This is a question specific to distributing App Bundles on Google Play for android.

After successfully uploading my packaged build on the google play console, downloading it to my phone via the Play Store, and executing it, I receive this error:

I have found multiple old threads of people having the same problem - but none of them uploaded AAB files (App Bundles) which are now requested by the Google Play Console. The packaged build runs fine when I install it via the Install_ProjectName-Android-Shipping_universal.bat which is located in the build directory.

I did create a keystore as described in the official documentation.

I did set Google Play up to automatically sign my releases.

I have spend 1.5 work days on finally publishing my first mobile game, hitting a lot of obstacles but now I seem to be stuck for good. I would really appreciate any help I can get. Thank you.

Update:
I’ve created blank Projects in 4.26 and 4.26, both C++ and BP-Only and set them up according to the documentations. The exact same error still occurs.

I finally found the solution. I missed the Google Asset Delivery System.

This video contains the exact steps that I’ve been missing.