I know this will be too late but I just installed one on my 2019 Commander.
I had to drill 3 holes. One in the front that they don't have pre-drilled in case you want to install a center rear view mirror. I also had to drill two holes in the back. All easy to drill, just have the bracket in place. I held the brackets together and in place with needle nose vice grips. Then I drilled through the holes in the bracket. I probably drilled all three holes in less than ten minutes. The vise grips made it very easy.
I am very happy with how the roof looks on my Commander.