After enabling ACH transfer payments for your invoices, Core sends your clients to the ePayment Portal where they are able to pay their invoices electronically. The invoice details are displayed on this portal and they are presented with the options to pay the invoice through credit card or an ACH payment.
In case of ACH payment method, you first need to verify your clients' bank account. To do so, they need to log into their bank account using the Plaid interface and share the account. The plaid interface lets them signal which account they'd like to link after they've successfully logged into their bank. After connecting, they can authorize a payment by entering their email on the invoices and checking the disclaimer. After the online payments are validated by Stripe, Core reflects the ePayments status accordingly in Core. Check Core Help Center for details.