ipad from 2015

If you're talking about Facebook Messenger (which requires iOS 12.4 or later), please identify your iPad model using these instructions:--> Identify your iPad model - Apple Support, then see this compatibility chart:

A1584 = iPad Pro 12.9" (wifi) 1st generation.

Yes, it supports, like all iPad Pro models, FB messenger.

Regards

Giulio

P.S. If relevant for you, this is a more complete table:

My pleasure