The wp_crm_system_gdpr_export_capability should return true or false (bool), and is used to determine whether or not the current user is able to export data.

By default, this filter will return true, as it is assumed that even logged-out users should have the ability to export data if they have the secret link to your GDPR page.

If you wish to only provide this to logged-in users, who meet certain criteria, you can use this filter to return false if the user does not meet your conditions.