Downloading a ROM for a game you do not physically own violates copyright laws in most jurisdictions. The legal and recommended method of acquiring a ROM is to "dump" your own retail GTA 5 Blu-ray disc using a compatible PC Blu-ray drive or a jailbroken PS3 console.
It is important to clarify a technical detail before the story: However, the digital version of the game installed on the PS3 Hard Drive (often referred to as a "ROM" by emulation communities) was notorious for its issues on the aging console. Ps3 Gta 5 Rom
The unpatched "Version 1.00" found on original PS3 discs contains certain unique details that were later altered or removed in subsequent updates. For example: Downloading a ROM for a game you do