How do i get the users profile id from the snapchat access token?

Question

To get the access token i followed instructions like this: https://marketingapi.snapchat.com/docs/profile.html#user-auth-via-redirect

and made this authorization link: https://accounts.snapchat.com/login/oauth2/authorize?client_id=df4c8722-9954-4214-ab24-360167398a1c&redirect_uri=https%3A%2F%2Fblizzity.de%2Fcallback%2Fsnapchat%2F&response_type=code&scope=snapchat-profile-api

but how do i get the users profile id and actualy do stuff with the profile now that i have the access token?

i also tried using this: How to use AccessToken received from Snapchat to fetch UserData?

but i always just get the response "unauthorized"