Setup can't find disc or specified file path Sims 3 Base game

Hi,

I downloaded the Sims 3 base game from here and I've mounted the two ISO files and have been trying to install them. I have Windows 8 and no disc drive (but I have a portable disc drive).

When the setup asks me to insert disc 1 to find the Gamedata\Shared\Packages\Fullbuild1.package. I clicked to open the StartDisk (named SIMS3) as instructed, it says it can't find the disk or file path. I tried to open the Disk 1 mounted image and same problem.

I re-extracted and re-mounted the images and started the install setup again, and still have the same problem. 

Please help, thank you

Here I was going to replly to you, but I decided a thread would be more helpful.
https://games4theworld.forumotion.com/t13595-setup-could-not-find-a-file-on-the-specified-path-or-disk#96945

Thanks