Hi @square,
I can’t find the function to create the subcategory
As far as I know, that isn’t something that osTicket is capable of. You would have to either request that the developers to consider that feature in the future, or create a pull request and code it yourself.
Every time a ticket is opened or answered, an email arrives with access to the direct link without making any registration
If I understand you correctly, you want to configure whether or not users have to register before being able to open a ticket. Technically, this is not an osTicket Awesome question — it is a question regarding osTicket’s core functionality. The best place for such questions is always osTicket’s forum where many more people will see it and you’ll probably get a faster response.
However, as a courtesy, I did a Google search for you and found the answer.
If you go to Admin Panel > Users you will find an option to Require registration and login to create tickets which you can toggle on or off.
I hope this helps.