I see you cross posted on this item.
The ubb control panel does not create a directory.
The first thing you need to do is create the directory with say a ftp program or your host control panel.
The ubb control panel does not create a directory.
Set the directory permission to 755.
Then got to your ubb control panel and set both path and URL. You can look at the ubb cp Control Panel ยป DB, Paths & URLs tab-Paths and urls section to get a clue.
Modify the path and url from what you checked above to point to the directory you created.
Select the test link. This will create a test file in the directory if successful.
The same method is used for the upload directory.
On my site I used.
mysite.com/forumuploads/attachments
mysite.com/forumuploads/avatars
This way I know all files in that location came from users.