Publishing AAB file for replacing APK file doesn't work

Hi,

I’ve tried to publish the aab file of an app that is already published on Playstore (based on apk file), but it doesn’t work.

The problem when I try to activate app signing on Google Play console is that the private key doesn’t match the certificate of the app (I’ve followed instructions in this link, even tried to upload output.zip Publish to Play Store (Android) with AAB - Thunkable Docs).

When I tried to upload my app with an apk file, it works. So I don’t understand what’s worng…