I believe that your install may have wanted you to type without the ‘:’ you are showing.
This works for me:
git clone https://gitlab.com/bradanlane/ros-i2cpwmboard
You will have another problem because doing a clone of this into ~/catkin_ws/src you will at catkin_make time hit a harder to resolve issue than this clone. Our image will not have i2c_smbus files
This is beyond my time to resolve this, tried a few things but no luck.
Sorry but this is the way of the world for use of shared code when the code you are wanting to use requires other things.
I see some hits on i2c_smbus issue like this but none resolved my try.
I have to give up as the weeds are getting deep and I gave it a try but no luck.
Good luck, it looks like a nice board to use, maybe there is different ROS driver somewhere.