Prestashop

Download the Sezzle module from the PrestaShop Marketplace.

In your PrestaShop back office, go to Modules > Module Manager.
Select 'Upload a module' , and select the .zip file that you downloaded on
your computer.
Go to Payment > Payment methods.
Find 'Sezzle', and select 'Enable Module'.
The plugin is now ready to be configured.
To learn how to install the plugin after you've downloaded it, you can also
watch the official PrestaShop video tutorial.

Configuration

In your PrestaShop back office, go to Modules > Module Manager.

In the Payment section, find Sezzle and select Configure. Fill out the following fields:

Live Mode : Enable or Disable for testing.
Merchant Id : Enter the Merchant Id that you got from Merchant
Dashboard.
Public Key : Enter the Public Key that you got from Merchant
Dashboard.
Private Key : Enter the Private Key that you got from Merchant
Dashboard.
Payment Action : Authorize and Capture for instant capture and
Authorize Only for just authorization(needs to be captured manually
from backoffice). Important: See Authorize Only vs Authorize and Capture for details about the difference between the two choices.
Allow Customer Tokenization : Enable to offer returning shoppers a
faster checkout experience by saving their card details.
Enable Widget : Enable for showing Sezzle widget in PDP and Cart
Page.

Payment Capture

Payment will be automatically captured during the checkout process.

Payment Action as Authorize Only
In your PrestaShop backoffice, go to Orders > Orders.
Select the order for which you want to capture the payment.
In the Payment section right below, enter and below information
and click Add
Date
Payment method
Amount
Change the Order Status to Payment Accepted if capture is
successful.

Payment Refund

In your PrestaShop backoffice, go to Orders > Orders.
Select the order for which you want to refund the payment.
Click on Partial Refund, enter the amount and click on Partial Refund right
below
For Full Refund, you have to fill up all the order related amounts in
respective places.
Change the Order Status to Refunded only if full refund is
successful.

Payment Release

In your PrestaShop backoffice, go to Orders > Orders.
Select the order for which you want to refund the payment.
Change the Order status to Cancelled, and click on Update Status.

Upgrading the module

If you are already using an older Sezzle PrestaShop module version earlier and want to use the latest version, proceed as follows:

Uninstall the existing Sezzle module.
In the Upgrade drop-down menu select Uninstall.
Manually remove the /sezzle folder from the /modules folder(if not removed during uninstall action).
Install the latest plugin version as described in Installation step.
Configure the latest plugin version as described in Configuration step.

Reinstallation

When you reinstall the plugin, the plugin takes care of most of its configurations and functions except for the items listed below. We recommend that you follow the steps here to make sure that when you reinstall the plugin, it won't pick up settings from a previous installation.

Order status

The plugin keeps the Awaiting Sezzle Payment order status

because existing orders might still use them. If you would also like to remove these statuses, first make sure that these are no longer in use.
To check if the status are is in use:
Go to the Orders page in your Prestashop admin panel.
Filter the orders for the Awaiting Sezzle Payment order status.
If there are any, move them to another status that you would like to use.

When there are no more orders using this status, you can delete the status from your order status list. - Configurations
The plugin keeps the AWAITING_SEZZLE_PAYMENT configuration fields in your database in case there are still orders in your system with the corresponding statuses. If you have already removed the status, you can also remove these leftover configurations.