How to install Gaussian in Ubuntu?

GROMACS version: 2018.1
GROMACS modification: Yes/No
The Ubuntu version I am working is 2018.04.6. I want to install Gaussian in Ubuntu. I came to know that it is not necessary to have a licence for the installation but I was unable to find a installer file and the command sudo apt install G09 did not work. So anyone please help me with this.
Thank you.