The availability of margin trading services is subject to certain limitations and eligibility criteria.
If you try to open a position with margin that exceeds your margin allowance limits, you will see a "Margin allowance exceeded" error.
(1) Increase your verification level in order to unlock higher allowance limits.
(2) Trade a different margin pair - margin allowance limits are independent for each currency.
For example, instead using the BTC/USD pair to go long on Bitcoin, you can use BTC/EUR instead.