Hi,
I have installed the alm plugin the very same way and I can confirm it works.
I think you get bitten by a bug in 2.4.7.1: In this version downloads don’t get logged (see [Solved] PDF download - PHP Fatal error - Application::getApplication() returns null - #3 by ctgraham).
Thus downloads do not appear in the usage stats. Consequently alm finds no metrics for any article as it considers only downloads!
If possible upgrade to 2.4.8 (which worked painlessly and smoothly in my case).
You might want to import the data about the downloads from your web-server log. If you want to do that but are unsure how I am glad to help you.
Greetings
Hermann