Building Extensions (Mobile Support): Due to requirements recently communicated to us by Apple, Extensions support on iOS devices (including the ability to test on iOS) is now restricted to Apple Developer Program members.
If you have released a mobile extension: Your extension no longer appears on iOS. Twitch will contact you soon about adding iOS support.
Update from the docs: If you develop a mobile Extension for iOS, please make sure you have an Apple developer account, and then fill out this form to request iOS support.