What you see is the new way App Inventor is required to scan the QR code and transfer the apk to your device. Google changed security procedures and MITs solution is to use your device browser app to facilitate the download.
This is how downloading a non GooglePlay app using the QR code works on some devices. The new way to download was required by Google's new security procedures. The apk download uses your device's browser so it may seem strange compared to what some of you are used to seeing. Here is what I believe you need to do:
1) Before you scan the QR code, set ( Check ) the Unknown sources box in your device Settings. Perhaps Security> Unknown sources . Setting this now allows your phone to download an app that is not in GooglePlay with a minimum of fuss. It is **important** to set this now rather than go through the messages that tell you you are attempting to install an app not from Google Play and are you sure you want to do that. Of course you want to download your own app.
2) Scan the QR code using Companion.
3) Wait while the app downloads (you may see a download symbol in your device Title bar or you might not depending on your Android version). The icon looks a bit like a check box over a small line and should show on the upper left of your device screen and probably is blinking.
4) When the download symbol disappears (stops blinking) from the Title Bar, look at your device's notifications. You should see a notification that indicates " xxxxx.apk Download complete". where xxxxx is the app you downloaded. If you see the notification:
4a) Click on the notification. This action continues the installation.
If you do not see the notification, there is probably a message on your Browser. Scroll down with the browser until you see the message to download.
6) A screen should appear probably indicating "Do you want to install this application?" .
7) Answer Next
8) then answer Install ... wait
9) then press Open to open the newly installed app.
10) Smile. Hopefully the apk will now be installed and will work on your device.