The Sims 3 Installation help!

I have a Mac, so if this topic could be moved somewhere more appropriately then please do so. I really need help. I was following the Sims 3 MAC Guide, and I created the .dmg files for The Sims 3 Ultimate Collection. I created the disk images for the base game and all the expansion packs I wished to download beforehand like it told me, and I was starting to install the base game. It stopped me and asked to insert disk 1. I tried to put in the path/file for which I had put the game .dmgs in and even the disk images but it said it could not recognize or find anything. The guide didn't mention anything about this, and I searched around for anyone having a similar problem and I could not find an answer.


I've been at this for 3 days. The first time, I had the original base game downloaded from Origin, but every time I tried to install my expansion packs from the Ultimate Collection, it kept saying I did not have the base game installed when I did, in fact, have it on my computer, (playable and all.) I even tried to use the manual update patch on the original base game, and it said the same thing. So, I uninstalled everything and decided to install the base game from this site instead, hoping it'd recognize it as installed when I tried to get the expansion packs. But now I am stuck on this, do I have to mount the disks I created? The guide did not say anything about that, it simply said to create them and then install the base game and expansion packs accordingly, with no extra instructions of the disk images I had just created. I'd really appreciate some help or something who knows how to fix this give me a step by step guide themselves? Thank you, and I'm sorry for the bother. I tried to include a photo of the pop-up.

i got that the other day it was because i extracted all the files onto a usb stick to install on a different machine but i think it didnt send over properly or stick is on its way out , so i then put it on an external hard drive and it installed and worked   i did originally think it was because my broadband turns itself off every now and then and it had damaged the download