I have had a 40' x 60' pole parn with 6"x6" treadted poles. I am planning on pouring a concrete slab. I live in South Alabama where freezing is short lived and rarely below 26 if then. People do not usually use rock under the slab here. I was wondering how much footing if any I need between the poles?

I don't quite understand the question. Are you asking how deep to sink the poles or what distant to space the poles?

No, the post are set. I am going to pour a concrete slab in the building. I am wondering about the depth on the outer edges between the post. Do I need to dig any footing or do I need a deep footing? Will 4 " do or do I need 12" footing?

You should still make a conventional downturned slab footing. Freezes are rare ( there in Al) , but nevertheless eventually you will get one and the frost heaving will easily ruin the slab. Then it costs three times as much to fix it.

4" of 2B gravel then 4-6" of concrete is usually the norm in the Northeast for a floating slab in a pole barn. Can't see it being much different down your way.
Around the poles install 3/4" rigid insulation. This will act as a "bumper" around the poles for the concrete. Along the outer area of the post, nail a PT 2x6 or 2x8 (depending on backfill and grade along the barn) to use a outer form.
You may want to saw cut control joints from pole to pole, if not you may end up with wondering spider cracks in your slab starting at the post then extending in to the field area of the concrete.