Depending on how many quail you intend to keep will determine the size/shape of your enclosure. If building a ground aviary, I would allow for 4 sq. ft. per bird...you could do with less space but it is always better to go bigger with gamebirds. It is also better to have adequate height to the pen, so you don't have to bend over to get into the pen and for easier access for feeding/watering and maintenance.
You will want to feed them a complete and balanced ration gamebird feed of at least 24% protein.
You can furnish the pen with stumps, large smooth rocks, fountain grasses, small smooth river stones, limbs to climb on if they want too! The enclosure should include a sheltered part so they can get out of the elements if they choose, rain and muddy conditions can be very detrimental to a quails life.
Most people raise Bob's in pairs. They can be successfully raised in a community pen as long as it is big and the male to female ratio is adjusted to that size of enclosure.
My 'on-ground' pens are 125 to 150 sq. ft and I run 25 to 30 birds in each pen. Usually 2 cockbirds to 20-25 hens...sometimes 3 cockbirds.
My above ground or wire floor pens are 12' x 3' x 16" and I usually run chicks in them for grow out purposes or until they are ready to move to the ground pens. These I run all males or all females so there's less bickering, arguments, and bloody fights occurring.
HTH