Error

Classified Listing Plugin Version 1.2.15
PHP: 7.4.5
Theme: https://ww.wp.xz.cn/themes/bizdir/
Website URL: covolunteer.help

Steps to reproduce:
1) User navigating to https://covolunteer.help/my-account/
2) User enters relevant info under Register
3) Click blue Register button
4) This error is thrown:

Warning: call_user_func_array() expects parameter 1 to be a valid callback, class ‘Rtcl\Controllers\Hooks\AppliedBothEndHooks’ does not have a method ‘new_user_notification_email_user’ in /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/class-wp-hook.php on line 287 Warning: Cannot modify header information – headers already sent by (output started at /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/class-wp-hook.php:287) in /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/pluggable.php on line 943 Warning: Cannot modify header information – headers already sent by (output started at /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/class-wp-hook.php:287) in /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/pluggable.php on line 944 Warning: Cannot modify header information – headers already sent by (output started at /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/class-wp-hook.php:287) in /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/pluggable.php on line 945 Warning: Cannot modify header information – headers already sent by (output started at /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/class-wp-hook.php:287) in /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/pluggable.php on line 1281 Warning: Cannot modify header information – headers already sent by (output started at /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/class-wp-hook.php:287) in /srv/disk1/3399043/www/covidcrisis.atwebpages.com/wp-includes/pluggable.php on line 1284

Please advise this is a charity site with an urgent timeline to deploy for helping those in need.

The page I need help with: [log in to see the link]