Here I can only recommend:
1. Check the game with a good antivirus, or better yet several, because it is unknown where and how a copy of the game got to such a site.
2. Make saves periodically. Because there is a possibility that some plot mechanisms may break and in the next version you will have to return to an earlier save.
In general, my personal attitude towards “illegal” copies of games is that more checks should be used with them.
Since some sites may simply provide a copy of the game, while others may embed something into it for personal enrichment.