On Click and Gutenberg Button Block

Dear @zipadoo ,

Thanks for getting back to us.
First of all, please, try to create the popup by following this article:

Open On click /On hover/On load Popup via CSS class.

As soon as you will have the popup created, please, open a page with the Gutenberg editor and follow the steps from the screenshots:
1. https://prnt.sc/wlo3po
2. https://prnt.sc/wlo44g
Just insert the shortcode of the popup by changing the popup id and the text, clicking on which, will make the popup appear.

Please, give it a try and let us know in case of any questions.