Start11 does not offer that option, although you are not the first to ask. Your best bet is to create a New folder somewhere on your C: Drive, and then create the folders you want to PIN to the taskbar and place them in this folder. Now, add shortcuts to the items you want in each folder and name them so they appear in the order you want to see, as they will be displayed alphabetically. Make sure to check "Show folders as submenus."
Once you have this set up, PIN the main folder to the taskbar as a Folder Menu and place it next to the Start Button. It should always keep it's place. The one caveat, is that there is only one level of hierarchy. Notice you can set the taskbar icon to a custom icon.
Pinned to Taskbar (below)

Pinned to Start11 menu (below)
If you want multiple levels of hierarchy thru the folders, you can pin the folder(s) to the Start11 menu; right-click and select "Open folder as a menu." However, this will only work with the Windows 10 style.
