Size of pot

Depends mainly if you’re running autos or photos. This might be the only time I’d recommend autos. Unless you wanna wait til late summer to harvest photos. If you don’t mind splurging on soil - I’d go 10 gallon autos (lowest 5 gallon) Or For photos I’d be doing 25-100 gallons Don’t do in the same pot unless you’re doing like a long rectangular raised bed.

After looking back over your dimensions am I reading that correctly 38' long, 14' wide, 5.5' tall? If that is correct I would think about possibly tilling the dirt with compost and amendments and just growing from the ground. 5.5 feet shrinks quickly especially when you add over a foot of height from the pot. Also takes sativas out of the running as they tent to grow tall and stretch, would require constant training from mid veg to mid flower.

Both answers are great! Covered everything I was going to say.

From what I have seen you do not really want multiple plants in the same pot, they end up competing for resources, and they will end up shading eachother and when they bush up will cause airflow issues and possible rot/mold issues. Pot size really depends on how big you want plant to be. Also depends on if you are using fabric vs plastic as the air pruning of fabric allows a bigger plant to grow/a plant to grow longer without root bind. I generally plan a gallon per foot, but that also depends on strain and training I have planned.. some grow in 5 gallon buckets others 100 gallon bag