Do they make a post hole digger that will fit the Max 28?
I think an issue you will want to consider is the lift height and how high you can get the auger bit off the ground.
What diameter post hole auger ?
Once you use a hydraulically driven post hole digger. You will wonder why anybody fools around with a pto driven unit.
A post hole auger mounted to the loader bucket is best of all.
I would assume a Max28 is the following tractor ?
TractorData.com Mahindra Max 28 XL tractor information