Where is the pie menu I recently installed Blender 2.80 and started with watching tutorials. But in the first tutorial there are pie menus that should appear when holding/clicking Shift-S.
However when I do that I get a totally different menu, the 'insert keyframe menu', and not a pie menu like in the tutorial.
Now I used to work with Maya, so I might (can't remember) have set the hotkeys in Blender to Maya-style during the installation, (I'm not sure if I did or if there is such an option.) 
I also work with a Wacom pen and tablet and not with a mouse. but that shouldn't be the problem.
I tried to change some settings in the addon preferences, but that didn't solve it. 
Any idea how to find the default pie menus?
You can find all this functions in the Object/Snap menu (or Mesh/Snap if you're in Edit mode).

In Edit/Preferences/Keymap, you can set the very first parameter to "Blender" if you want the same keymap used in most tutorials.

If you want to change this particular shortcut, or know the shortcut defined in your keymap for that pie menu : in Edit/Preferences/Keymap, type "snap" into the search field. Under "3D view", locate "wm.call_menu_pie". You can change the assigned shortcut by clicking on it.