I just downloaded and installed Royalty as per the documentation using the "Quickstart Installation" after removing the previous Joomla install. I am running Windows 10 using XAMPP on a local machine before migrating it to a production server with the following:

Apache/2.4.46 (Win64) OpenSSL/1.1.1h PHP/8.0.2

I've successfully created a Joomla site locally on two different Win 10 machines previously but after following the instructions and the video I get the following error messages when I try to launch the Royalty template:

Fatal error: Uncaught Error: Undefined constant "MB_OVERLOAD_STRING" in C:\xampp\htdocs\digitalpaint\libraries\vendor\joomla\string\src\phputf8\utf8.php:38 Stack trace: #0 C:\xampp\htdocs\digitalpaint\libraries\vendor\composer\autoload_real.php(66): require() #1 C:\xampp\htdocs\digitalpaint\libraries\vendor\composer\autoload_real.php(56): composerRequire205c915b9c7d3e718e7c95793ee67ffe('2fb9d6f23c8e8fa...', 'C:\\xampp\\htdocs...') #2 C:\xampp\htdocs\digitalpaint\libraries\vendor\autoload.php(7): ComposerAutoloaderInit205c915b9c7d3e718e7c95793ee67ffe::getLoader() #3 C:\xampp\htdocs\digitalpaint\libraries\cms.php(36): require('C:\\xampp\\htdocs...') #4 C:\xampp\htdocs\digitalpaint\includes\framework.php(18): require_once('C:\\xampp\\htdocs...') #5 C:\xampp\htdocs\digitalpaint\index.php(40): require_once('C:\\xampp\\htdocs...') #6 {main} thrown in C:\xampp\htdocs\digitalpaint\libraries\vendor\joomla\string\src\phputf8\utf8.php on line 38