To trade on margin from DEGIRO, you will need to upgrade your account to Active or Trader. For this you will to complete two appropriateness tests and sign additional conditions in the trading platform
Only the Basic profile may be upgraded. If you have a Custody profile, and wish to trade on margin, you will first need to open a new account with a Basic profile.
It is free to upgrade. Once you have upgraded to Active or Trader, your availble margin will be included in the Available to Trade amount. It is not necessary to enable the Debit Money feature separately once your account has been upgraded.