"The Group 'i2c' does not exist."

Having trouble with giving USB access on Linux Ubuntu 20.04.

Listed below is the terminal output:

myusername@myusername-desktop:~$ sudo adduser myusername plugdev

The user 'myusername' is already a member of 'plugdev'.

myusername@myusername-desktop:~$ sudo adduser myusername i2c

adduser: The group 'i2c' does not exist.