I downloaded the Create a World BETA some days ago, and I can't even open it for the first time.
I haven't found anything about it here, except from a post which was closed by the forum, they said it's a known issue and I could find the solution on another side, but there was no working link and looking for my problem on google didn't help.

The Sims 3 Create a World Beta has crashed!
Exception information:
Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

I copied this text from somewhere else as my game is in German (which may explain my bad English... I was almost too embarrased by my English skills to start this post), and just added the "Beta".
I've looked everywhere. There are two possible solutions for this problem:
1)To edit a file named "Default" in the CAW folder or
2)making CAW Large Adress Adware.

None of them worked for me.
I have Windows 7 and 4 GB RAM.

Oh, and I have Late Night, Generations, Pets, Supernatural and Island Paradise installed.

there is tons of information about it on this forum, you just need to look in the right place. In the menu at the top is the create tab, click on it, select Sims3 and create-a-world. In that forum you can search, but you can also click on one of those threads on a blue background. They mention a lot about issues with caw. It's riddled with it.

On your issue. Do you have upgraded to 1.69 patch? If you have you need to download the latest version. If you stayed on 1.67 you need that version of caw. I'm not sure where to find the previous version 1.67, at the moment.

I had updated my game before I installed CAW. Maybe I'll just have to give up.

It is possible to reset your game to 1.67. There are instructions floating around. You can get earlier versions of CAW here: https://cawster.wordpress.com/ CAW can be frustrating. I've been trying to get it going for years now, have yet to release a world.