Fatal error: Uncaught Error: [] operator not supported for strings

I am testing the plugin on a local installation, because it would solve my problem to publish many files of technical documentation and tutorial.

I am using Apache/2.4.54 (Win64) OpenSSL/1.1.1q PHP/8.1.10 and MySQL 8.0.30.

I get this error in settings page:
Warning: Array to string conversion in?C:\laragon\www\osbo-staging\wp-content\plugins\simple-file-list\includes\ee-list-settings.php?on line?402

Fatal error: Uncaught Error: [] operator not supported for strings in C:\laragon\www\osbo-staging\wp-content\plugins\simple-file-list\includes\ee-list-settings.php:421 Stack trace: #0 C:\laragon\www\osbo-staging\wp-content\plugins\simple-file-list\ee-admin-page.php(228): include() #1 C:\laragon\www\osbo-staging\wp-includes\class-wp-hook.php(308): eeSFL_BASE_BackEnd(”) #2 C:\laragon\www\osbo-staging\wp-includes\class-wp-hook.php(332): WP_Hook->apply_filters(”, Array) #3 C:\laragon\www\osbo-staging\wp-includes\plugin.php(517): WP_Hook->do_action(Array) #4 C:\laragon\www\osbo-staging\wp-admin\admin.php(259): do_action(‘toplevel_page_e…’) #5 {main} thrown in?C:\laragon\www\osbo-staging\wp-content\plugins\simple-file-list\includes\ee-list-settings.php?on line?421

I understood it is an array declaration problem (maybe) but I can not find where ti fix it.

I think the plugin could be great, but if I can not test it I can not use it. Help, please.

Thanks in advance.