Hi,
You didn't follow all the instructions there.
It says:
In the < ul class="hikashop_tabs_ul"> element. Then add a div with content after the "ul" thanks to:
<div class="hikashop_tabs_content" id="hikashop_show_tabular_custom">
<!-- Your div content -->
</div>
However, you didn't add that div after the ul.
You need to put your "echo $this->element->download;" inside that div as explained in the documentation I gave.
Also, if you look at the id of that div and the id of the li, you can see that both start with hikashop_show_tabular_custom
And if you check the id of the div and the id of the li for the description, you can see that both start with hikashop_show_tabular_description
So basically, each title/content combination must have an id starting with hikashop_show_tabular_ plus a word specific to the tab.
That's how the system knows which content is linked to which title.
It also means that if you add several tabs, you can't use the same id but different ones for each tab.
For example, instead of:
<li id="hikashop_show_tabular_custom_li" class="hikashop_tabs_li ui-corner-top"><?php echo JText::_('Zubehör & Download');?></li>
<li id="hikashop_show_tabular_custom_li" class="hikashop_tabs_li ui-corner-top"><?php echo JText::_('Anwendungsvideo');?></li>
you should have:
<li id="hikashop_show_tabular_custom_li" class="hikashop_tabs_li ui-corner-top"><?php echo JText::_('Zubehör & Download');?></li>
<li id="hikashop_show_tabular_custom2_li" class="hikashop_tabs_li ui-corner-top"><?php echo JText::_('Anwendungsvideo');?></li>