The reference looks weird, there's information missing?
Check the item in the database, does it contain all the necessary metadata?
Zotero doesn't seem to be working with Apple Pages?
No, that's right. Unfortuntely there is at the moment no working Zotero plugin for Pages.
I receive the error message "You have modified this citation since Zotero generated it. Do you want to keep your modifications and prevent future updates?"
If you've made manual changes in the citation, that is, the grey field generated by Zotero, you will get this message. (If you want to edit a citation, click Add/Edit Citation.) If you choose Yes, your manually made change will remain, but the citation will not be updated if you make changes to the item's metadata, or change citation style. If you click No, the citation will be updated, but the manual edit you did will be deleted.
I want to cite a dataset but there is no such item type in Zotero. What do I do?
Zotero has yet to create an item type for datasets but recommends that Document is used until a type is available. You can find more information on how to cite datasets here.