How to dry out a damp basement and stop mildew?

Use a dehumidifier and place buckets of damp rid around

can you install a small exhaust fan -- like a bathroom fan to remove excess humidity? you can buy box columns at most home improvement centers - come in 2 halves that you simply put together around the post and anchor to the ceiling and the floor.

A dehumidifier that you do need to empty often, so you would need a utility tub or some other water outlet down there. That is the only way we could figure out to solve the problem years ago, when we had a basement. Windows did little to help if anything.

Here is a good start....https://www.familyhandyman.com/basement/affordable-ways-to-dry-up-your-wet-basement-for-good/view-all/

To dry out the basement I would run a dehumidifier. You can spray the mildew with a mix of bleach and water, and just let it sit. For the basement poles there is a kit you can purchase to install around the poles.

it sounds as though you don't have proper air circulation down there...running a dehumidifier would certainly help but you could investigate whether there are sufficient cold air returns. For making the columns, frame the pole using 2x4 or 2x2 's. You can then either dry wall the sides or use wood the size of your frame...trim out the top and bottom of the pole with crown moulding type trim to your taste

I've heard about keeping charcoal around (buy a bag and just open it - sort of like you do with baking soda in the refrigerator) for the moisture/damp air.