It took me too much time to get it, i wasnt paying much attention, i was just trying to smack him to tame him like other dinos, but it was way easier. You just have to go to Moschops and look what they are asking to be tamed(at the top below their name and lvl), if its berries then its super easy, if its something else you just have to put it(anything they are asking for) in quick access slot, and feed it, then wait until it ask again to be feeded, do this and Boom! you have your coward Moachops ready XD.
(Same technique can be used for few other dinos)[few? Idk i just noticed 2-3 dinos that asks to be tamed like this, btw i am newbark player :) ]
For Gathering Resources:
Just put it to Wandering, and if they are still folowing you just Whistle "Stop" for them only and see they'll go for resources :). Then just collect resources from their inventory time to time as your need.
Also, as far as i read, you cant Ride them on Mobile version.