If you have enabled two-factor authentication (2FA) via an app such as Google Authenticator on your Degiro account, synchronization should be possible.
In this case, Powens will ask you for a confirmation code generated by the app you used to set up 2FA, such as Google Authenticator (read Degiro help article).
Please note that two-factor authentication via SMS is not supported and will not allow you to synchronize your account.
ℹ️ At Degiro, there is an alphanumeric password to enter your accounts via the website and a numeric-only password (therefore different) to enter them via the app. You will need to type the alphanumeric password used to enter via the website. The app password does not work to aggregate Degiro accounts on Finary.