Both motors and elastics are used for catapulting. The motors are directly coupled to the catapult arm so there’s no release mechanism aside from the motors themselves.
For long range shooting the elastics + motor power provide enough energy to propel a ball into the high-goal.
As for short range, the motors are run at a lower power which essentially acts as a brake for the elastics. Otherwise too much energy would be imparted to the ball.