This pertains to the new >August 2021 Google Play app signing scheme that you can opt into, which I did.
The B4A IDE needs to automate all steps to creating an "upload key" for the Google Play Console where we upload our packages (now called Bundles). Google apparently signs the app using our upload key, certificate or whatever they want to call it, but I don't have it, I don't know how to generate one, etc.
I've been a coder for 35 years and I have to admit that this private/public/key/certificate crap is a nightmare. If the B4A IDE isn't helping me any, then I'll have no choice but to migrate completely to the dreaded but much used Android Studio. I want to keep using B4A but B4A needs to keep up with the times! Generate keys for us, save them whereever you like, but sign my app from the IDE automatically with whatever Google Play EXPECTS. I cannot believe I've been sitting here for 3 days googling how to do all of this and all I find is "keytool" examples and CLI commands that nobody on this planet could have figured out on their own in a short time. I now have an older APK app that has been removed by Google due to "non compliance" because I can't get B4X to generate what Google needs. It's ridiculous guys. I paid for this before it was free, so please don't say "it's free - get over it". To make matters worse, there are no real explanations in the forums, but mostly the same key/certificate/private/public jibberish all out of order.