That's surprising. Are you using all the rules for the companion correctly? At level 9, with a +4 proficiency and a 20 STR, the ape will be doing 1d6 + 9 damage with its melee attack (+13 against a favored enemy), and if you're using Coordinated Attack it does that twice.

A level 9 beast conclave ranger is getting +11 to hit with a longbow and doing 1d8+5, add 1d6 with Hunter's Mark, add +4 against a favored enemy, and add the companion's two attacks for +9 to hit with 2(1d6+9 or 13[Favored Enemy]).

Assuming no favored enemy and using the ape's reaction to attack, that's an average for the ranger/pet of 38 damage per round only at the cost of Hunter's Mark which you get to re-cast at virtually no cost once the targeted enemy drops to 0