The one thing to know about Jimdo
The widget is available where Jimdo allows custom HTML. If a plan or editor mode hides the Widget/HTML element, that restriction comes from Jimdo.
Where reviews belong on a Jimdo site
Use a full-width content area for a carousel or grid and a narrow column for a compact badge. The element follows the width of its Jimdo section.
Full-width sections suit carousel and grid layouts; narrow areas suit a badge.
Reviews and search results
The widget outputs review schema markup automatically. Whether Google shows a star rating depends on what the reviews are attached to — worth reading before you expect stars, because for a business reviewing itself the answer is usually no.
What does help either way: reviews on the page are content, and a page that answers what customers actually say is a page people stay on.