SH 5 dvd CAN'T install

[templarjack]

Good evening. I bought the steam version of SH 5 a few years ago but was disappointment when I found out that it does not support many of the mega mods for SH 5. So, several months ago I purchased SH5 again, this time the physical dvd version from amazon. I only got around to trying to install it tonight, however after inserting the disc, the install option in the menu is grayed out! What could the reason be for this and how do I fix it?

I would greatly appreciate any help! Thank you very much!

Pic is very related...