If you have trouble with installation follow these steps:
This video is a brief, but in-depth tour of how to use Zotero.
The below video will show you some incredibly helpful tips on how to work with PDFs in Zotero. Most helpful is how you can automatically rename the files names of PDFs with the click of a button! See 3:00 timestamp.
If you have Zotero 5 installed on your computer (current version as of Spring 2020) you'll need to install Zotfile so you can extract annotation information from PDFs and turn them into searchable notes within Zotero.