In order to be able to make a SEPA Direct Debit payment, a valid mandate is required. This means that you need the account holder's permission to direct debit their account. Officially, you will need a so-called 'wet signature' on paper for this. However, there are tolerated constructions to get permission otherwise.
What is important for you as a merchant is to show Mollie's name and collector ID to your consumer. This ensures that the account holder is aware of the fact that Mollie (or rather “Stichting Mollie Payments”) carries out the direct debit on your behalf.
Mollie's collector ID is: NL08ZZZ502057730000
Example authorization form
On the website of the Dutch Payments Association you will find a number of examples for drafting a so-called 'authorization form'.