Hello,
Your checkout workflow isn't showing any error message so it can be coming from a template issue, so you'll probably find the solution
there
:
HikaShop uses the core Joomla messaging system to display messages on your website so if you don't see any message when you don't enter correct information during the checkout process, that's probably because your Joomla template does not contain the tag to display Joomla messages: <jdoc:include type="message" />
After that, can you test it again and tell me if an error message is displayed ?
Thanks.