i need to make custom cron_schedule with custom interval time as a parameter into a custom payment gateway plugin wordpress

Question

i used the defoalt from the documentation to create a custom cron intervals in a custom plugin payment gateway:

i added in the construct the line: add_filter( 'cron_schedules', array( $this, 'add_cron_interval' ) );

and in the class body the method:
/**
 * Adds custom time intervals for the cron.
 */
private function add_cron_interval( $schedules ) {
      $options = get_option( 'inquiretimes' );
      $interval = ( ! empty( $options ) ? absint( $options ) * HOUR_IN_SECONDS : DAY_IN_SECONDS );
 
      $schedules['wpdocs_interval'] = array(
           'interval' => $interval,
           'display' => esc_html__( 'Custom Interval' )
      );
 
      return $schedules;
}

but when i view the cron schedules it doesn't registered yet! what's wrong as well as when i create schedule with the custom interval i created occurs an error!

public function registerCronJob() {
            
        if ( ! wp_next_scheduled( 'cronPerMinutes' ) ) {
            wp_schedule_event( time(), 'wpdocs_interval', 'cronPerMinutes' );
        }
    }

note that i added the below line in the constructor too: register_activation_hook(__FILE__,array($this,'registerCronJob'));