Do you see the zammad code snippet in your sourcecode?
Im running the zammad chat in a shopware site and it was a bit difficult to find where to place the code.
I placed it here:
/themes/Frontend/YOUR_THEME/frontend/index/index.tpl
{extends file=‘parent:frontend/index/index.tpl’}
{extends file=‘parent:frontend/index/index.tpl’}
{* Userlike Code *}
{block name=“frontend_index_header_javascript_jquery” append}
{/block}