People without a JIRA license are able to create a ticket through the portal but then can not view the ticket through said portal. So they're unable to reply to it etc etc. It's asking them to sign up?
It looks like you have an open portal. This allows everyone to send in requests.
However, if you want to show those issues to the customers that have send them in, they need to have an account. Otherwise, all the issues will be available to everyone visiting your site. This is, for some obvious reasons, unwanted.