Arobas Music (the developer) no longer sells GP5 licenses. They focus on GP8. However, you cannot legally download a full, cracked version from a torrent site without violating copyright law.
Guitar Pro 5.2 was a massive leap forward when it was released. Before this version, the software used basic MIDI sounds that sounded like a cheap video game from the 90s.
Download Guitar Pro 5 | Tablature Editor Software – Support
Arobas Music provides a dedicated Guitar Pro 5 Support Page where you can download the base software and individual RSE soundbanks for Guitar, Bass, and Drums.