For Astropad Standard, we don't have shortcut for the dock.
If the Dock is hidden:
On your iPad, tap 2-3 times the very bottom, at edge of the screen.
This should reveal the dock; but we would suggest keeping the dock visible if possible.
If not hidden:
You can adjust the iPad screen view with "Move & Zoom" to access them.
Move & Zoom mode can be activated by holding down the white ring button, or selecting it in the sidebar.