Trying to activate "Project Nami Full Text Search" plugin

[AposKaragiannis]

I'm trying to activate "Project Nami Full Text Search" plugin in Wordpress installed on Xampp server running on localhost. PHP Version 8.1.6 , projectnami ver.: 3.0.1

I get the message: Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, non-static method PN_Fulltext_Search::activate() cannot be called statically in C:\xampp\htdocs\prjNami\wp-includes\class-wp-hook.php:307 Stack trace: #0 C:\xampp\htdocs\prjNami\wp-includes\class-wp-hook.php(331): WP_Hook->apply_filters('', Array) #1 C:\xampp\htdocs\prjNami\wp-includes\plugin.php(476): WP_Hook->do_action(Array) #2 C:\xampp\htdocs\prjNami\wp-admin\plugins.php(194): do_action('activate_pn-ful...') #3 {main} thrown in C:\xampp\htdocs\prjNami\wp-includes\class-wp-hook.php on line 307

Thanks!