That SHAPE of room is ideal for a pair of small HPS (2 x 250w) or a 4' t5 fixture.

In that size footprint, I would start an entire package of seeds (10) expecting to finish with 4-6 females, which is about right for that space if you pinch each one into a little bush when it is young, and allow each one about an 18" circle of floor space. You will be potting-up and killing the males after week 2 of flower- it WILL seem a bit crowded in the the first 2 weeks of flower; this is normal.