rulset not read from private repo

[neurohrer-mms]

i extend a ruleset which is located in a private repository. Unfortunately the ruleset is not applied. i guess - as i couldn't find an error - that it simply can not be accessed. The url in the settings is targeting to the correct file.

If i create a .spectral.yml file with a content like

extends:
  - @mycompany/rulesets/rules.yml 

where as the module is also behind a login, i can not use it.

how can i resolve that? do we need some more settings to handle the credentials?