The Schema Faq Block extension adds a new FAQ Block to the Gutenberg Blocks list under Schema section, which allow entering frequently asked questions.
This extension requires Schema Premium version 1.0.7 and up to work properly.
1- Adding FAQ Block
The Faq Block extension once enabled, it will add a new Block to the Gutenberg Blocks list under Schema section.

You can use this block to add FAQ where ever you want them to show on the page, and the extension will automatically append the schema.org markup.
1- Add FAQ
When you add a new Faq block to the editor, you will see a repeated field that will give you the option to add as many frequently asked questions rows as you like.
2- Preview FAQ
You can switch the block to preview mode, in this mode the fields will show on the right sidebar and you will be able to preview your FAQ block while editing it.

Related:
Also, read about how to add FAQPage schema markup for additional details.