The WP 6.3 beta 2 does not work on Xampp Control panel v3.3.0, compiled on April 6, 2021. This Xampp is a straight out of the box installation, with Php v7.

I tried twice using the zip file, a third time with WP 6.2 and the beta plugin, then did the same at InstaWP, which worked. using the Duplicator plugin I cloned it to my localserver, only to not work again.

The backend and frontend do not match, the FSE nagigation block is a disaster, the template files look fine in the Site Editor, but on the front, some blocks do not render, or do not render correctly, the columns completely lost the width settings for each column, etc, etc…

I can produce a video if needed…