Once you have registered a domain name with the .be extension with WebSelf, in order for it to be activated, you must first (as the domain holder) validate the domain with DNS Belgium.
As of November 2020, the registry (DNS Belgium) performs verification of registrants' identities in case of suspicious registrations. The registry performs verification before the domain name is activated to stop potentially fraudulent registrations and to prevent domain names from causing damage.
When the registry sees that the holder data is incomplete or incorrect, they temporarily delegate registrations to the name servers of DNS Belgium, so domains are registered but not yet active. The domain's URL points to a page with the details from the verification message. In the verification message, the registry asks the registrant to prove their identity. The registrant provides the registry with the required documentation to confirm. Once the registry has received and approved the proof, the domain is activated.
IMPORTANT:
In March 2023, all registrants can verify their details online and are no longer required to send identification documents via email.
The domain holder is responsible for carrying out the validation, directly on the DNS Belgium website. The verification is done automatically with Itsme or eID.
You can find the verification page here: https://www.dnsbelgium.be/en/registrant-verification