A loan can be recorded as follows:
Create a manual account called "Loan" or any other name of your choice with a balance of 0 (Go to 'Banking' > click the account at the top to open the drop down menu > 'New Account' > select 'Create manual account' > 'Next' > Fill in account name and balance > 'Save').
You should have another bank account already saved in Debitoor which the loan was paid into. - Your uploaded bank statement should show the income for the loan.
Click on the income entry and mark it a "transfer from another account."
Select the account you created called "Loan."
Enter a description: e.g. "income from loan."
Now the balance of the account is minus (e.g. -30000 if you got a loan for 30000).
Now go back to your main account with the incomes and payments of the loan.
For each loan payment, click on the outgoing payment and mark it as a transfer to another account.
Select the account you created for the loan (for example, if you pay 1000, the balance of the new "loan" account should then be 29000).
When the balance is back to 0 (or positive after interest), it would mean that the loan is fully paid off.