Installation and setup

Requirements

CS-Cart, CS-Cart Ultimate, Multi-Vendor or Multi-Vendor Ultimate 4.17.2 to 4.21.x; PHP 7.4 to 8.3 with cURL and OpenSSL.
A Scalapay merchant account. From the Scalapay Partner portal you need the API key (sandbox and production keys differ) and, for the widget, your merchant token.
Euro set up as a currency of the store (Administration > Currencies). Scalapay takes euro only.
An HTTPS storefront and a cron job on your server.

Steps

Install. Add-ons > Manage add-ons > upload the package (kv_scalapay-x.y.z.zip) and install Scalapay Payments. Enter your licence key in the add-on settings (License section).
Connect. Orders > Scalapay > Connection. Choose Sandbox or Production. Paste the API key of that mode (sandbox: leave it empty to use the public test key of the Scalapay documentation) and the widget merchant token. Press Save and test: the add-on asks Scalapay for an order that cannot exist; the answer “unknown order” proves the key works.
Webhook. Copy the webhook address shown on the Connection page (https://<your shop>/index.php?dispatch=kv_scalapay.webhook&c=0) into the Scalapay Partner portal, developers section, field “Webhook Url”. The webhook is optional but recommended: the customer’s return and the cron settle payments without it too.
Payment method. Administration > Payment methods > add a method, processor Scalapay. Choose the Scalapay product (Pay in 3, Pay in 4, Pay later, or any). Create one method per product of your contract if you want to offer them separately. Do not put Scalapay first in the list; CS-Cart pre-selects nothing by itself.
Settings. Add-ons > Scalapay Payments > Settings: capture mode, order statuses, the minimum and maximum of your contract, the widget (see Configuration).
Cron. Add one of the commands shown in the settings (every 5 to 10 minutes): php /path/to/admin.php --dispatch=kv_scalapay.cron or https://<your shop>/index.php?dispatch=kv_scalapay.cron&key=<secret>.
Test. In sandbox mode place an order with the test card 5200828282828210 (success) or 4000000000000341 (failure). Sandbox orders are marked “TEST MODE”; switch to Production when you are done.

Uninstall and updates

Uninstalling keeps the Scalapay payment records (payments, captures, voids, refunds) and the connection, so after a reinstall or an update refunds of older orders still work from the order page; the payment methods are linked again. Tick Delete payment records on uninstall in the settings before uninstalling to delete everything for good. Capture or void open delayed authorizations first.

Updates: upload the new package over the installed one; the add-on brings its tables and settings up to date on the next admin page (self-healing upgrade).