Go to ecartpay.com and head to the Integrations section.
Click on Download to get the .ZIP file corresponding to the Prestashop module.

Access your PrestaShop account and, from the dashboard, open the Modules > Module Manager menu.
In the top right corner, click on Upload a module.
Select the .ZIP file you downloaded and click on Open to start the installation.
Once the installation is complete, the Configure button will appear. Click to continue with the setup.
The system will ask you for a public key and a private key.
To obtain them, open a new tab and go back to ecartpay.com.
Log in with your account or register if you do not have one yet.
Inside the Ecart Pay panel, in the left sidebar menu, select Integrations > API.
Copy your public key and private key.
Paste both into the corresponding fields within the PrestaShop module.
Click on Save to finalize the setup.