Is it normal to be asked for an advance fee on a withdrawal?
Never pay to receive a withdrawal. If they wanted to send you money, they could deduct the fees from the sum they claim you own in your account.
It's a common scam to be asked for money so that you withdraw your funds. In fact, if you pay, they'll find a different excuse and ask you again to pay them, while you in reality never had any money on their website.
Your account balance might show $10k, $100k, $100m but don't be fooled by their values displayed on their website. Never ever pay to withdraw any bitcoins.
Seek help from your local authorities.