Stuck in "Setting up..." during installation

Dear all,

I'm trying to install Norton Mobile Security on a Android 5.1.1 phone.  However, when I run it for the first time, it's stuck on the "Setting up..." screen.

Basically, after installing, I run it.  I agree to join Norton Community Watch (though this choice doesn't seem to affect things) and select "Agree & Launch".  Then, "Setting up..." appears with a spinning blue circle.  However, it's stuck doing this.

I've tried turning off the screen saver to prevent the phone from going to sleep.  I've switched to WiFi.  I cleared the cache and re-did everything from scratch.  I uninstalled it and reinstalled it again.  I even rebooted the phone.  None of these steps worked.

I'm not sure what else I can try.  If it was merely downloading files, I wouldn't mind.  But looking at the cache, each time I check, it is always around 5 MB.  i.e., it isn't growing in size based on how long I wait before I stop it.

Any suggestions would be appreciated -- thanks!

Ray