Current User:
%appdata%\Microsoft\Windows\Start Menu\Programs\Startup
Personal Profile:
C:\Users\<user name>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup.
The startup folder for all users is:
C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup.
If the folders are missing it’s fine to create them. You many need to enable “show hidden folders”
Shortcut to current user press “WinKey + R” and enter:
shell:startup
Shortcut to all users press “WinKey + R” and enter:
shell:common startup