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