How can I track that someone visited the following URL of my website http://www.website.com/mypdf.pdf.
I tried using a Page View trigger on a Page View tag. I'm completely new at Google Analytics so not sure how to proceed. Most people are going to be going to that pdf directly via URL, as there is no link to it on my website, but I really want to be able to track how many people view it.
Thanks in advance!
You cannot track PDF views with the help of GTM. GTM for web is a javascript injector, and one cannot inject Javascript into a PDF document from the browser.
One way to circumvent this is to have a gateway page, i.e. have the click go to a HTML page that counts the view before redirecting to the document in question (naturally you could use GTM in that page). Since people go directly to the PDF URL this would require a bit of scripting - you would have to redirect all PDF links to your gateway page via a server directive, count the view and then have the page load the respective document.
Another even more roundabout way would be to parse your server log files and send PDF requests to GA via the measurement protocol (actually many servers allow to have log writes redirected to another script, so you could do this in realtime). I would not really recommend that approach - it's technologically interesting, but probably more effort than it is worth.
The short version is, if you are not comfortable fiddling a little with your server setup you will probably not be able to track pdf views. GTM does not work on PDF files.