If you're set on getting an old version of Photoshop, your safest path is buying a legitimate license from Adobe (though CS2 is no longer sold), or subscribing to the modern Photoshop (which has a 7-day free trial).
While Adobe once released a version for existing license holders to use after servers went dark, it was never intended as "free" software for the public [2]. Safe & Free Alternatives adobe photoshop cs2 portable google drive hot
To edit a Photoshop file, you'll need to download it to your computer, open it with Adobe Photoshop CS2, make your edits, and then save the file. If you're set on getting an old version