Error in Emails settings

I am trying to customize the email messages of admin/instructor/student, but I got an error while loading the settings and got an email told me that there is an error:

/home/nibrasac/public_html/wp-content/plugins/learnpress/inc/class-lp-file-system.php.
error message: Uncaught Error: Call to undefined method
WP_Filesystem_Direct::exist() in
/home/nibrasac/public_html/wp-content/plugins/learnpress/inc/class-lp-file-system.php:157
Stack trace: #0
/home/nibrasac/public_html/wp-content/plugins/learnpress/inc/class-lp-file-system.php(127):
LP_WP_Filesystem::file_exists('emails/plain/ne...') #1
/home/nibrasac/public_html/wp-content/plugins/learnpress/inc/admin/meta-box/fields/email-content.php(76):
LP_WP_Filesystem::get_contents('emails/plain/ne...') #2
/home/nibrasac/public_html/wp-content/plugins/learnpress/inc/admin/meta-box/class-lp-meta-box-helper.php(108):
include('/home/nibrasac/...') #3
/home/nibrasac/public_html/wp-content/plugins/learnpress/inc/abstract-settings.php(87):
LP_Meta_Box_Helper::output_fields(Array) #4
/home/nibrasac/public_html/wp-content/plugins/learnpress/inc/admin/settings/email-groups/class-lp-settings-emails-group.php(71):
LP_Abstract_Settings->admin_option_settings() #5
/home/nibrasac/public_html/wp-includes/class-wp-hook.php(303):
LP_Settings_Emails