Dear, You can add it via use custom code, please install and switch your site to use Jobica Child theme, then add customm PHP code in file functions.php of Jobica Child Theme.
Code:
add_action('noo_register_form_start', function(){
$prefix = uniqid();
?>
<div class="form-group row required-field">
<label for="<?php echo esc_attr($prefix); ?>_first_name" class="col-sm-4 control-label"><?php esc_html_e('First Name','jobica')?></label>
<div class="col-sm-8">
<input type="text" class="form-control" id="<?php echo esc_attr($prefix); ?>_first_name" name="first_name" required placeholder="<?php echo esc_attr__('First Name','jobica')?>">
</div>
</div>
<div class="form-group row required-field">
<label for="<?php echo esc_attr($prefix); ?>_last_name" class="col-sm-4 control-label"><?php esc_html_e('Last Name','jobica')?></label>
<div class="col-sm-8">
<input type="text" class="form-control" id="<?php echo esc_attr($prefix); ?>_last_name" name="last_name" required placeholder="<?php echo esc_attr__('Last Name','jobica')?>">
</div>
</div>
<?php
});
Best regards.