Apk not installing on phone

We made an app using MIT App Inventor. I scanned the apk file on to MIT App Inventor on my phone. I can't find where the apk file is going? Kindly help

How did you transfer the apk file to your phone?

Hello Geetha. You are scanning with the App Inventor Companion on your phone?
If so, have you updated it recently? You can download it from Google Play Store.

(Assuming you are using Android)

Yes. We already did. I am scanning with MIT Companion only. The moment I scan the code, the screen disappears.... I tried to download. The same disappearance happens with the download function as well.

Scanned what? Companion qr code or Apk qr code?

After I click on "Build" and the Build apk option, I got two options 1. download apk 2. scan qr code.

So, you scanned QR code.
Now issue is with browser you are using. If its is not allowed to prompt for download location then it'll silently download files to path specified in download settings. Mostly it is Downloads dir.

Use the companion app to scan the qr code.

This should then offer you an install option.