They didn't really issue above authorized shares. The series C aren't convertible and they aren't common shares. They were preferred shares that Delcath can just keep creating series D, E, F, so on. These preferred shares just have voting powers equal to about 800k commons per share for RS vote.
They maxed out on authorized common shares but they are far from maxed out on authorized preferred.
But preferred have little value compare to common shares because Delcath isn't paying any dividends, or interests on these preferred.
The preferred shares are only worth it if they can convert into common shares and sell in the market to get the money back and some more.