<?php if($block->checkIsLogin()){ ?>
    <?php if(\Magento\Framework\App\ObjectManager::getInstance()->create('Magento\Customer\Model\Session')->getCustomer()->getGroupId() == 4){ ?>
        <?php if ( $block->checkIsSeller() ) { ?>
            <li>
                <a href="<?php echo $this->getUrl('marketplace/seller/dashboard'); ?>"><?php echo __("Seller Dashboard"); ?></a>
            </li>
        <?php } else { ?>
            <li>
                <a href="<?php echo $this->getUrl('marketplace/seller/become'); ?>"><?php echo __("Register Seller Account"); ?></a>
            </li>
        <?php } ?>
    <?php } ?>
<?php } ?>