Layer Groups are only available in the desktop versions right now.
I would suggest to implement this feature in all Version (Windows 10 / Android / iOS) to get a consistent workflow through all applications.
For me the missing layer groups are very annoying when I work on different devices. Cause all the time I have to make a copy and merge the files later or I'm loosing my layer groups after saving and then I have to regroup everything in the desktop version. I try to avoid groups anyway, but sometimes my artwork has a lot of layers, and it's necessary to organize them.