No additional configuration required after installation and activation proccess.
You can go straight to the editor and start using Pinterest widgets. You will find them under “Pinterest widgets” section in block inserter.
To add your first widget go to any page or post edit page. Find Gutenberg editor blocks inserter (“plus” icon at the left top corner of editor). Click and look for “Pinterest Widgets” section. Here you can widget that you want. After adding widget you will have to insert Pinterest
You can read more about using every widget in the following documentation articles.