[Hustle Pro] Hustle Pro generates fatal error

Yesterday I talked with one of your members of the support team via chat. We tested everything, like disabling all plugins, switching themes but still if only Hustle Pro is activated (nothing else and just the WordPress twentytwenty theme) it generates a fatal error.

Could you guys look into this, why this is happening? I setup a staging environment for you guys to use for testing at https://staging.dhk-kozijnen.nl.

Kind regards,