I have installed the template Noavah (J4) demo website several times.
First of all, I had to delete the file: autoload_psr4.php every time in the folder: admnistrator/cache/. As is known, the website ran afterwards.
When you log in to the admin area, numerous admin modules are represented DOUBLE. Theoretically, I could simply hide the duplicate modules, but I don't know whether the demo installation has other "damages"?