Messenger App install
Since recent Messenger update V.366/386.1. Unable to install FB Messenger on my iPad. Any help appreciated.
There are many reports of issues with FaceBook Messenger. Many users also report that deleting both the FaceBook and FaceBook Messenger Apps from the iPad, prior to restarting and reinstalling the Apps, will resolve the problem:
Delete apps on your iPhone, iPad, and iPod touch - Apple Support