<?php
function my_custom_popup_trigger( $is_loadable, $popup_id ) {
	if ( $popup_id == 123 ) {

	  if ( $my_condition == true ) {
	      $is_loadable = true;
	  }
	  else {
	      $is_loadable = false;
	  }

	}
	return $is_loadable;
}
add_filter( 'popmake_popup_is_loadable', 'my_custom_popup_trigger', 1000 );