The core rulebook covers everything you need to know to play Shadowrun 5e, including:

Also, be wary of potential errors; some community complaints mention the third printing referencing incorrect page numbers, so having the community-updated Master Index Edition is essential.

Once you have acquired the legitimate "Top" PDF from DriveThruRPG or Humble Bundle, you need to manage it like a pro. A 500-page PDF is unwieldy on a phone.