My sense of this with other formats (eg old DOS games) is that if I had legally purchased the game originally, then I feel ok about downloading it at a later date to play on an emulator (ie because I don’t have a 5.25" disk drive, or perhaps even threw out the disks not envisioning that someday there would be emulators capable of running old software on modern machines). This may or may not be in violation of copyright law… if I had managed to dig up a machine that had a 5.25" drive and a CD burner, for example, I could transfer the software into a format I can use on a modern machine, and I’d be in possession of exactly the same thing I downloaded. In that case downloading from a website is just a different mechanism of transferring my old data to a format that is useable on today’s machine; I don’t think it matters that it’s not a copy of “my” original disk, because both “my” copy and the website copy are themselves copies of an original. In the case where I threw out my disks, it might be sketchier - by throwing it out, do I lose my license to use the software? I didn’t transfer the license to anyone else, except maybe Oscar the Grouch if he finds my disks. But the law may be such that physical possession of the original disks is itself the license to use the software or copies thereof.
I just re-read your original post - Are you using a PlayStation emulator to play it? In which case (depending on how the emulator works) you might just be able to use your original CD-ROM (mount that drive in the emulator, or whatever). Assuming of course that a PlayStation emulator, if it exists, is itself legal.
Or are you looking to get the PC version of the game, which is likely different? In that case I would say you are on thin ice, legally. Owning the PlayStation version doesn’t give you license to use the PC version of the software.