I'm a software developer so yes, I do know how steam cracks work. I've got my setup configured so that normal steam cracks do not set off my virus protection. The fact that this one did is notable. Not sure if you're aware, but viruses can indeed by hidden inside .dll files. The fact that it is named 'steam_api.dll' means literally nothing about what is inside. That being said, I opened the file up to look at the code it contained and didn't see anything that stood out as strange.
i think you are not familiar with scene or don't know what scene is, you can search on wiki or google. This game comes from TENOKE, it's completely safe.
You can check the hash of the .iso and compare it with predb sites, like:
https://www.srrdb.com/browse/category:pc/order:date-desc/1