Keystore files missing from Android source download (Starter plan)

Hello,

I downloaded my app's Android source code from App Studio to create release builds from source, following the "Build Android from Source" guide. The build file references upload.keystore (alias "upload") and release.keystore (alias "release"), but neither file is included in the download.

How can I get these two keystore files for my app? Please contact me privately at the email on this post, since I'd rather not share signing details in a public thread. My App Studio account uses the same email.

I have an update to publish on Thursday 1 October, so a quick answer would be much appreciated.

Thank you!