I can try to help with the pdf downloads part: it doesn't need to enable the "Article view counts". It should be presenting the data by default.
What you need to make sure is that your OJS is gathering and processing the usage metrics. This is done by the usage stats plugin. It should be activated, and also the acron plugin should be activated if you don't have a cron job running to process the stats.
Can you check those settings?
Also, if everything is ok, check your ojs files folder, at usageStats/archive and see if there is any files there. If yes, it's because the system is processing your stats. After that, check if the metrics table has records.
Now, related to what you said about the article view counts. What you mean it seems not be working at all?
I'll wait for your answers. Thanks,