After you enabled the ACH add-on feature your customers need to verify their bank account details, before they can pay via ACH.
First the bank account details need to be added and then the customer should receive 2 micropayments and use the amount of those micro payments to verify their bank account.
Add Bank Account Details
Adding bank account details can happen in two ways:
1) Either your customer needs to add their bank account details
Please ask your customer to visit the client portal and click the "Add a Bank Account" button on the profile page:
Once they click the "Add a Bank Account" button they need to fill out the following form:
2) Or you add your customer's bank account details
You can add your customer's bank account detail on the customer detail page by clicking the "Add Bank Account" button:
Once you clicked "Add Bank Account" you should see this popup:
Verifying the bank account
Once the bank account details are added your customer should receive 2 micro payments and enter the amount of those two payments on the client portal (it could take a couple of business days before the client receives micro payments):