I would mark the spots where the water accumulates the deepest and drill holes thru the concrete there with a hammer drill when it’s dry. There should be crushed stone under the concrete and the water will drain away into that. You should be able to do that in less than 15 minutes. 1/2” hammer drills can be had for around $ 50 from Harbor Freight.
I personally don’t like concrete floors in pole barns. My workshop and porch area is concrete but the storage area (boat, tractors, implements, camper storage) is crushed and compacted stone. No big deal if something drips a little water or oil onto that.
There’s not a crack on any of my concrete (I’m in upstate NY where it gets real cold in the winter). My nephew poured and finished it 5 years ago. He’s very good at flatwork.
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