The user tokens are different than an application token.
The user token allows a formula URL button to edit a record without the user needing to sign in. The downside is that you will not know who actually clicked the button as it will always show the user of who owns the application token as the [Last Modified by]
The user tokens are obtained by clicking on your name at the top right and then "Manage Preference". That is where you can create user tokens and assign their use to specific apps.
My guess is that the user token is either not correct or is not enabled for the app you are editing.
