Firstly you will need to download the Trust Payments module from the PrestaShop Official Addons Marketplace.
Click “Download” and follow the instructions.
Your browser should download the Trust Payments module in zip format.
Next, sign in to the Control Panel of your PrestaShop Store.
On the navigation menu on the left, within the "IMPROVE" section, click Module > Module Manager.
On the top right of the “Module manager” page, click “Upload a module”.
You can either search and select the module file, or alternatively drag and drop it into the box present.
If successful, you should be presented with a green tick and a success message. The module should then be visible at the bottom of the page under “Payment”.
Unfortunately, the product documented here is currently only available in English.