Hi,
HikaShop (starter) propose login and registration features during the checkout.
This is all ok when I put the site in maintenance mode (Joomla) because I then have to login in Joomla to enter the site. Hikashop automatically fills out my credentials then. But when I open the site up, this step doesn't work any more.
I'm sorry but I'm not able to understand that part of your message.
You have to login, but can't create an account. So I'm really stuck with the login part. If that is fixed I'm done.
If you already have an account (user/email + password) you can't create the same account with the same email.
In that case it means that you want to use "guest checkout" ; where you do not create Joomla accounts. But that feature is provided by commercial editions of HikaShop.
Regards,