Custom WordPress plugin

I need help with an offline wallet system plugin for Gravity Forms. Users can pay for orders using the Wallet system immediately the form is submitted(based on the total cost), and Admin can add or deduct from user's wallet. HOW THE GRAVITY FORM WORKS.... * The form is used to collect order * The charge is based on the user selection from the list of available options * Once the user makes a selection and he/she is ready to submit, he or she will be deducted from their wallet (if the order amount is upto the amount in the wallet) If the amount is not upto the wallet balance, there will be a notification of "Insufficient funds" I have the Gravity forms webhook add-on, what this does is that... It will submit the order after it has been successfully paid for to an external API for processing. I just need the "Wallet Plugin" to act as a payment gateway for my users... Only the admin can add or deduct from the wallet. SAMPLE LINKS; [login to view URL] [login to view URL] So I just want the form to popup(will be using elementor page builder for that)... The user fills the form and clicks the submit button, the money gets deducted first before submitting. And the order gets delivered to the API for processing