You may use the rest API node in the workflows to push submissions from the Clappia app in real-time to your custom database.
Help Guide Link: https://help.clappia.com/help/workflows-rest-api/36
But If you want to dump the submissions directly to your database rather than using Clappia's database, you can request the Clappia team for personalized service for an additional fee, after which you will be able to dump all of the submissions to your custom database.
You can drop your request on this link https://one.clappia.com/app/CON421756 39or call +91 9641861031 for any inquiries.