I'm not sure what to do for Exchange problems. I don't use it and it doesn't seem to have a lot of support these days.
You can upload patterns you make to our Sims 3 SwapShop
Here's how to do that:
1.) Go to this board linked below -
Sims 3 Patterns
http://www.carls-sims-4-guide.com/forum/index.php?board=24.02.) Create a New Topic about your pattern. (Click the New Topic Button on the right top - Just above the stickied posts.)
3.) Give some details about the pattern.
4.) Share some photos of the pattern, if you'd like. (The link below can help with sharing photos.)
Topic: Sharing Photos on the Forum
http://www.carls-sims-4-guide.com/forum/index.php?topic=22892.msg403211#msg4032115.) Go down under your post where you see the words Attachments and other Options. Click that to open it up.
6.) Attach the file - Click the Browse button, and browse to where you store your Sims 3 files. Usually you find the files in the Sims 3 Export folder.
Go to: ----> Documents > Electronic Arts > The Sims 3 > Exports
Look for the file you want to share. Select it, and click Open. The file should now be attached and will be added to your post as a downloadable file.
How To: Export Files
http://www.carls-sims-4-guide.com/forum/index.php?topic=20751.msg380782#msg380782