You can set up payment gateways from here for the Invoice, by default Easy Invoice Support PayPal payment gateway, and if you want to add other gateways you can use any of the payment extensions from our available extensions lists.
General:
Test Mode: While test mode is enabled, no live transactions are processed. Use test mode in conjunction with the sandbox/test account for the payment gateways to test.
Enable proceed to payment button: You have to enable proceed to payment button to use payment gateways, if you do not enable the proceed to payment button, you can’t make the payment.
Proceed to payment button link: if you do not have any payment gateways set up then you can use the custom link for that proceed to payment button but if set up any payment gateways then no need to set up any link here.
Thank you page: You can set up thank you page. The user will be redirected to this page when payment success.
Payment Gateways: Right now you can select only one payment gateway PayPal but if you add additional gateway extensions, you will see those gateways listed here so that you can check one of the gateway from here.
PayPal:
To use PayPal gateway you have to set up the PayPal gateway from here after enabling the gateways above.
PayPal Email Address: Your PayPal email address goes here.
Gateway Label: You can change the gateway label for users. They will see what you write here.