[momoninja]

Is it better/no difference to do sudo su or usermod? I used sudo su but not really sure either way.

Ok, I assumed you are using a linux machine.

su is a program to gain admin rights on your machine.
sudo is a program to do certain tasks that require admin rights. The user has to be member of the sudo group or have the rights for the command in /etc/sudoers
usermod is a program to modify a user account

You want your user to be in the group dialout to interact with the microcontroller that is accessible via usb via the device /dev/ttyACM0.

So when you are using a standard linux distribution like ubuntu your user is normally in the group sudo. So with the command I sent you you should then be able to add your user to the group dialout and use the companion application.