You can design an email template from the Setup Email Template page in the PK4Connect Wizard screen.
There are some pre-designed email templates in the "Pre-Designed templates" folder as Simple 1 3 Col, Fancy 2 1 3 Leftsidebar, Sidebar Right, Letterhead Right Logo, etc. You can select any of the pre-designed templates, add or remove extra content in the template per your needs, then save the template for later use.
Or, you can also click the Create my own tab in the Setup Email Template screen and create your own email template. You can drag and drop the tiles from the right-hand side of the template screen to add text, images, buttons, merge fields from Salesforce, etc., for designing parts of your email template.