Is it possible to use the GTA V Steam Files for the Rockstar Download

Hi I know the title is a bit confusing but let me clean things up.

I bought my friend GTA V with a key which is supposed to activate on the social club. So no steam. I have the steam files. Is it possible to use this files so he don't have to download the game first? So we could play tonight? Please let it be possible. If it is working how?