Hey I couldn't figure it out either as you can see I even made a comment about it
How I got it was by reading the comments here:
installing F1 VM instead of VMOS or virtual master and then activating the x-posed(root)in that and then from add apps downloading mystic messenger and pm injector
And then after that pm injector automatically gets root access as you open it and then start the mod menu by following the process written up there (first keep mystic messenger running and then open pm injector in new tab and click process and select Mystic messenge)