Data management system and integration with Squarespace forms

Hi,

I´m working on a site for a Personal Trainer and we want to use Squarespace form builder. The data from our form is very personal so we want the data from this form to be send to some kind of "secure" and "GDPR friendly" database or data management system. But which one? Any ideas? It should have an integration to Squarespace or to be connected through Zapier.

Thanks for your help.

Best regards
Jacob