HELP: Dark Souls Remastered on Steam Deck Failed to Initialize Steam

I'm new to this, I understand the basics from downloading switch games but I've encountered a block. I downloaded Dark Souls Remastered for PC off of csrin, I tried using Steamless to extract my game files but it asks me what you want to open the Steamless.exe file with. Not knowing what to say I decided to add the DarkSoulsRemastered.exe to Steam (it asked me the same question when opening it in desktop mode) and try running it there, but It says "Failed to Initialize Steam" after a couple seconds of loading. I have it running through Proton 8.0 in Compatibility settings & switched it to older versions, but It said the same thing. Is there a way to get past this error, or the file opening error? Am I supposed to put the files of the game into my steam files?