Missing "Open" button on Google play store

I know Flutterflow has a one-clic deployment feature, but I would like to learn doing it myself. So here's what i did. I downloaded the APK from Flutterflow. Then I opened it in Android Studio, and built a signed AAB from there. I did all the preliminary setup in the Google play console, and created a closed test release using the AAB file. After 4 days waiting for Google to review it, I received the link to be shared with my testers....

by the way if someone here volunteers to test it, please let me know.

Then I downloaded the app to my phone, in order to run a first test.

Unfortunately, I could download and install it on the phone, but after that I could only see the "uninstall" button, not the "open" button. Also the app icon did not appear anywhere on the phone. I could find it in the list of settings>applications, but there is not much I can do from there. I noticed that in that list, the app did not have the proper icon (only an android robot) and no authorization (internet or file) was granted to it...which seems weird.

I tried also the "internal test" track, but same thing happens

Any help is welcome

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