The iPad Pro 6-in-1 Hub is compatible with the M1 iPad Pro. However, the default black grip is designed for older iPads and isn't thick enough. To use it with the M1 iPad Pro, you want to swap with the extra grip that is included in the packaging with the one that is on the Hub. The other grip is thicker and will support the size.
After installing the mounting plate that states "With Screen Protector" on the hub, plug it into the iPad as it's illustrated in the image below. (the longer side of the plate should be on top of the iPad screen)
The blue tiny power LED will light up. The hub is ready to go.
Plug in a charging cord to the hub will charge through the Hub to the iPad.