Building a Box in a basement im unsure about

Ive been contructing a box for a little while and im unsure if this can be a healthy place for plants. The basement is stone rocks with dirt floors and something about the smell is off, maybe theres mold. Ive had 6 girls down there for about 2 weeks just under a light not in a box and they dont seem to mind it. What is the recommended quality of air? Theres not much air flow down there would it still be ok to suction and exhaust from there. Its a decent size basement. Or would you recommend suction from the our living space and exhaust outside or something? If i am exhausting outside we get some cold winters which might be a problem.

Thanks for any advice you may offer.

Watch for bugs , mites keep your temp to 70 deg
im interested also !!