I'm creating new categories but the links get broken. I'm sure I follow the normal process.

blueglassvision.com/iphone-6s-plus

Not Found

The requested URL /iphone-6s-plus was not found on this server.

It seems like every new link I create is like this. How can I solve this issue?

Hi,
It seems you are missing the index.php here.
Please use this URL: blueglassvision.com/index.php/iphone-6s-plus

This can be fixed through "mod_rewrite". Hope you will fix the issue.
If you need more information you can contact our support team at edukolkata.com

Thanks