Welcome. That's a super open ended question.

What size is the room this system will be going in?
What kind of lighting?
Sealed or vented room?
How long do you intend to veg the plants?
Starting from seed or clones?
Do you have cycle length constraints? For clarity, do you have to ensure you're harvesting in quarterly iterations, or less, or more, or will you be letting the plants determine the cycle durations?
Is it a custom build or pre-fab system like what Current Culture makes?

Probably come up with some more but those are a good start