This has all the red flags of a scam.
(1) You shouldn't have to pay money to withdraw money from your account.
(2) it is extremely uncommon and suspicious to ask for fees in bitcoin, a completely irreversible transaction that hides their identity.
I'm pretty sure your money is long gone. Chalk it up as a life lesson and move on.
Update: I looked at their website and they seem to be VERY focused on crypto, so the bitcoin thing might not be as much of a red flag. But it says in black and white on their FAQ "No, there are no fees for withdrawal."
Their site seems very fishy. Especially the part where their FAQ prominently asks the question "Is this legal" and gives a hand wavy answer.