This is an old post - but I'm a new member of the forum.
User-Forms are not included in the Mac version of Excel unfortunately, and Active-X controls are also not included. They were included in earlier versions of Excel for Mac and it's frustrating not to have them in the current version. The regular forms controls are very weak in the Mac version of Excel so I don't use them often. They cannot be formatted with a font/font size and end up looking pretty bad.
That said, I've been successful in using regular worksheets to replace the missing user-forms. Excel Tables work pretty well as replacements for list boxes. Data validation works well to replace combo boxes.
Excel tables also work very well to use in a "database way" for storing and retrieving data if they are properly set up. I use arrays to add/delete rows (records) and edit existing records. You can mimic some real database functionality using these methods.
Hope this helps.