No: You don't have to install anything. e2n runs as a cloud solution in our data centre and is therefore accessible on a current browser.
You can log in to the system via e2n.de. On your smartphone or tablet, in addition to accessing the system via a browser, you can also access the system via the "e2n perso" app.
You entered the access data yourself during registration or they were set for you as a user by an administrator. If you ticked the appropriate box, they were sent to you by e-mail.