They are asking you to pay a fee upfront in ETH approx $20k to send your BTC out to another wallet outside their platform.
Mate, this is an obvious scam attempt. They're asking you to send $20k in ETH for what? A crazy exchange if that's what they're asking. I can even trade on binance with just $10 and with the little withdrawal fees.
It's a scam attempt and for your first post, it's not really a good thing that you'll be going for that. This thread makes it as a warning for everyone who might encounter that website.