Can i come and workout outside with group of people? Or do i need to get a permit to run a one spot workout?

No permit needed. Just find a spot thats not in the way of the disc golfers.

No permits needed they just charge you for day use

The park is huve open areas people frequently workout yoga ect

Our baseball team always held cardio practice in the grass areas, with no problems.

Probably not because the park is mostly a frisbee golf course.