Bug after submit register user form

Hello.
Bug after submit register user form
version oc 8.3.0
php 8.0.30 and php 7.4.33

( ! ) Warning: <strong>Could not instantiate mail function.</strong><br /> in \osclass-v8.3.0\oc-includes\osclass\utils.php on line 684

Warning: Cannot modify header information - headers already sent by (output started at \osclass-v8.3.0\oc-includes\osclass\utils.php:2420) in osclass-v8.3.0\oc-includes\osclass\core\Cookie.php on line 88

Warning: Cannot modify header information - headers already sent by (output started at \osclass-v8.3.0\oc-includes\osclass\utils.php:2420) in \osclass-v8.3.0\oc-includes\osclass\utils.php on line 2434

Please solve this problem

Sigma Osclass Theme 1.6.0 by MB Themes

@Alireza SSE
Well, fix your localhost.
Error is pretty clear and self-explanatory.
Do not use localhost if you have no clue about what you doing.

Could not instantiate mail function.
This error typically indicates that your server isn't configured to send email using PHP. The most reliable solution is to install an SMTP plugin and configure it with a trusted email provider. If the issue persists, contact your hosting provider to verify server email capabilities or to request SMTP credentials.

Thanks