At what resolution do you play? Are the 4060mb only for Far Cry Primal or the whole setup running with all applications together? If it is too much for your card, try to go down resolution (if you have higher than 1080p) or Anti Aliasing methods. I didn't read following article fully, so I don't know his settings. He says even on Ultra HD (4k) he is below 4060mb:
> http://www.guru3d.com/articles-pages/far-cry-primal-pc-graphics-performance-benchmark-review,12.html
You could have use Google yourself to find these information. I did it for you. ;-) So, the 4 GB VRAM seems normal for highest settings. You just could give more information what hardware you have and what settings (resolution).