You have to hit the corrupted part of it it will bulge out of it and then if you destroy all them it will be tamed the taming effectiveness depends how much damage you do to the creature more damage lower taming effectiveness lower damage higher taming affectedness that is how you tame the giant desert manta.
How to tame a titan:
Step one: piss your pants
Step two: grab a mek
Step three: shoot the glowy thingnies
Step four: piss your pants some more
Step five: destroy all of the glowing orbs until it falls down.
Step six: click tame kaiju
Boom you have a titan
Pro tip: Don't use explosive weaponry and really bad rexes with no saddles like the devs did. Fab Snipers for taming it with little/no collateral damage, actually decent rexes + imprint + saddles to kill it (Probably not for this flying one tho lmao).