WEB API POST METHOD

Hi all,
I have the following problem with this web API integration: if I make the POST call on Appian it works correctly, but if I try to make it outside of Appian (ex: from my computer's prompt) it gives me the following error: 401 check credentials.
For the POST call I used the curl command using as url the one written in the web api.
I attach screenshot of my API call on Appian and the settings used. Instead the GET calls I can do them correctly.

Thanks in advance!