Access Teamfolder via API

Hello there,

currently I'am trying to get access to our Team-Folder via the API, but I have some troubles with that.. I'am using the authentication via Access-token and the connection works, but I didn't find a way to see the full team workspace. Either I only see the home folder from the user who created the access-token or I only get a "Team_shared_folder". I already tried it with the 'Dropbox-API-Select-Admin' in combination with the member_id of a Team-Admin and with 'Dropbox-API-Path-Root' in combination with different namespace_ids in Header. 

e.g.:

calling ../2/team/team_folder/list 
only with authentication in Header, response with

{team_folders: Array(1), cursor: "AADzUBJG4-_...", has_more: false}
cursor: "AADzUBJG4-..."
has_more: false
team_folders: Array(1)
0:
content_sync_settings: []
is_team_shared_dropbox: true
name: "Ihr Team's shared workspace"
status: {.tag: "active"}
sync_setting: {.tag: "default"}
team_folder_id: "263521..."
__proto__: Object
length: 1
__proto__: Array(0)
__proto__: Object

calling ../2/team/team_folder/list 
with authentication and 'Dropbox-API-Path-Root' => [".tag" => "namespace_id", "namespace_id" => 263521...]  in Header, response with

{team_folders: Array(1), cursor: "AABKGcil8JPcyA7...", has_more: false}
cursor: "AABKGcil8JPcyA..."
has_more: false
team_folders: Array(1)
0: {team_folder_id: "2635...", name: "Ihr Team's shared workspace", status: {…}, is_team_shared_dropbox: true, sync_setting: {…}, …}
length: 1
__proto__: Array(0)
__proto__: Object

Do I have to use a OAuth2 user-auth? I'am a bit frustrated.. don't find my failure :/

EDIT: I found this Link: https://www.dropboxforum.com/t5/API-Support-Feedback/How-to-list-the-contents-of-a-team-folder/td-p/258310

And I noticed, that I have issues with ../2/files/list_folder[/continue] in combination with the 'Dropbox-API-Select-User' header,too. I tried it with the team_member_id and account_id from .../2/users/get_current_account . I get a bad request back for it.. Don't know why :/