Root user?

Hello,

will try install sundtek tv-stick on the Firmware. But i need an Root Account.

admin@RT-AC66U:/tmp# sh sundtek_netinst.sh
Busybox installation
In order to install this driver please run it as root
eg. $ sudo sundtek_netinst.sh

But sudo not on the Router.

How can i become a root acount on the router?