No need for an app with the "responsive" layout of themes used by the forum software--it adapts to the given screen size automatically. Most good sites today do this, so visitors are not forced to clutter up their devices with unnecessary and/or unwanted apps.
Tapatalk is known among admins to be buggy, unreliable, poorly supported, and a security and privacy risk to the forum members who use it. I dumped it from forums I run about three or four years ago. Good riddance.