I'd be glad to help and provide insight about setting up an ACH Debit in QuickBooks Online (QBO).
Yes, you can set up an ACH Debit to pull a customer payment. However, in order to have this you'll have to have an active account of QuickBooks Payments. You can check this article to learn more about connecting your QBO Payment account to QBO.
After connecting or linking your payments to QBO. You'll now have to set up or enable your account so your customers can pay invoices online. Here's how:
Go to Settings, then select Account and Settings.
Select the Sales tab.
Under Invoice payments, select Edit, then select the payment options you want.
You can also enter Payment instructions. They will show on all invoices regardless of the template, when payments are enabled.