the easiest thing to do is to call your brokerage and talk to them. Dial 1 800 669 3900 and yes, i know that number by heart. I see you have an ameritrade account as do I.
Hit 1 for client services.
They are really helpful.
They can talk you through what is allowed on your particular account, and i strongly believe it would need to be a margin account. Then they can tell you the margin requirements. I just looked it up and it is among the very highest level of margin requirements.
And some of the things you said are slightly off. There is a ton written about the mechanics behind brokerages restricting trading in certain stocks, the clearing houses that set the cash necessary to trade certain high risk stocks, and which brokerages are best suited to extended the float necessary to make market in volatile stocks like gamestop. Really, theres' a lot out there explaining it and a couple seconds of googling and 15 min. read will make you in the know.
But that said, let me do you a straight up solid and tell you: don't short this stock. You are most llkely going to get killed. This is not the place to cut your teeth.
I traded it maybe a dozen times last week, made a little once, lost a little a couple of times, and broke even a few times, all for a net very small inconsequential loss. Mostly i just wasted the time. And i would not dream of shorting it, truth be told.
Good luck. If you want to short something, try something less volatile and call Ameritrade, they will give you the straight scoop in a nutshell.