Hi,
After using the QR code, your app download starts immediately, right?
After the download is completed, you’ll see a notification in your smartphone saying “Download competed”. If you click that notification, it will try to open the app that you’ve just downloaded. 
Otherwise, after the download is completed, you’ll have to go to the “Files” icon on your smartphone and find the recent downloaded files.
Every smartphone is slightly different, some call it “Downloads”, “Files”, “Documents” or “Archives”.
Or search on Google for your smartphone’s name and “download folder”. After finding the file, if you open it you can install the app permanently (and the icon appears in your screen).
 
Let me know if you were able to make it work.
Thanks,
Rui

Rui
Thanks and I was able to do that, for my phone.
Appreciate the help a lot.
For my wife’s (Android) phone, I am thinking of just mailing and asking her to install – the apk — does this work?

Exactly, you can send her the .apk file attached in an email for example. She downloads the .apk file and opens to install it. That works just fine too

Thanks. It does!!
 
Appreciate the help…I’m looking now to use GPS sensor…If you have a lesson on that, please post it…

Yes, MIT App Inventor supports the GPS sensor and you can find it on the “Designer tab” under the Palette “Sensors” > “Location Sensor”.
Here’s more information: http://ai2.appinventor.mit.edu/reference/components/sensors.html#LocationSensor
There’s also a great tutorial using the Location Sensor here: https://docs.google.com/document/d/1V1Zm5cYoa12KVb_cTlfelSfyUkW7IH2WPHUoTa02XaY/pub

Thanks Rui. You are incredible!!
Keep it up man!!
 
Will post my findings on this GPS application.
 

You’re welcome. I’m glad I could point you in the right direction.
Let me know your results!