I think its much easier to tame with 2 people, 1 shooting darts, 1 throwing bolas, you can even do this tactic with 1 person but it require some practices and timing.
Tapejara
The Tapejara is a versatile and highly maneuverable pterosaur known for its three-person saddle. While it may not have as much stamina and weight carrying capacity as other creatures, it has unique benefits in combat. The Tapejara can land on trees and other vertical surfaces, allowing both the pilot and the passengers to use weapons. Its rudder-like fin make it one of the few flying creatures able to hover and strafe side-to-side.
Player-written tips for taming, using, and fighting the Tapejara in ARK: Survival Ascended & Evolved.
Bola cannot keep your furture friend forever
Go build 4 pillar around and place ceiling on the top
Now it can fly..but not to the sky
Not sure about PC or Console but on mobile rex doesn't agro you when you are riding this guy