Purchase a used physical copy from a local retro game store or eBay, then rip your own ISO using a PC with a compatible DVD drive and software like ImgBurn or DVD Decrypter.
Before we discuss how to acquire the file, it’s critical to distinguish between legitimate and illegitimate use.
Use a tool like HashCheck or 7-Zip to verify the checksum. A clean ISO should match these common community hashes (approximate):