My experience is with a 2019 FX.
There is no procedure from Zero, known to me, on how to mount/adjust the motor. My suggestion is to sit down and study the mounts. On the left, the motor is attached snug to aluminum brackets. On the right, there are 4 adjusting bolts. Mark one that is easy to get to and remove it, learn how it works then put it back like it was. Nothing will fall apart.
The belt is centered on the front sprocket by adjusting the motor mounts. To move the belt left on the front sprocket: loosen the two right rear motor mount bolts, turn the big silver adjusters in slightly (1/4 turn), retighten the bolts. Check it and repeat if needed. After tightening the back twice, consider next extending the two right front adjusters (slighty).
Visa versa to move the belt to the right on the front sprocket.
Don't extend the two right rear adjusters too far or the motor mount will conflict with the swingarm.
The left motor mounts are fixed and the adjustments to the right motor mounts should not be extreme.
Usually, after each small motor mount adjustment, a wheel adjustment is necessary.
This truly makes the motorcycle run smoother and more quietly........after the loud cursing.
Hope this helps.