Upload your app version is a really simple process.
First, you need to get your AAB file from our support team.
Entering to your account
To update the version in the Play Store, first, go to the next link:
https://play.google.com/apps/publish/
Log in with your credentials, and you will see a screen like this. With all your apps created.
Select the app you want to update.
In the next screen, click on Production > Create new release.
Upload your version.
In your Play Store account, you are going to upload your ".AAB" file (You can drag and drop the file). Automatically will upload the version.
Just add the new release notes (what's new in your app, new features, fixed bugs, etc.).
Click Save...
If you want to publish your app right after the app review, skip the next step.
Congratulations!