Zotero for iOS is the best way to work with your Zotero library on an iPad or iPhone.
While there is no way of contacting Zotero for help directly (via phone, email, etc.), Zotero provides documentation for using the program and discussion forums on their website.
Zotero Forums document user discussions, which can be particularly useful for technical issues and troubleshooting. You can start new discussions or review previous discussions.
Zotero - A Quick Introduction (6:26 mins) - Nov 2020