I see colored tag on the [Zotero for iOS](https://www.zotero.org/support/ios) page, but I don’t see them after I download them, either iphone or ipad. How do I set them up?
so, it only show tag when using zotero storage? I can see my tag on group libararies(sync attachment files using zotero storage) but not My library which use webdav to file syncing. all my data syncing option have been select.
I'm not sure what you mean here. You should see the same tags on all devices. If you don't, see Changes Not Syncing and provide the requested info. (In this case the relevant change would be modifying a colored tag.) It might also help to take a screenshot, upload it somewhere (Google Drive, Dropbox, etc.), and provide a link here, or email it to support@zotero.org with a link to this thread. (We'll respond here either way.)
This doesn't have anything to do with file syncing, no.
Upgrade Storage
This doesn't have anything to do with file syncing, no.