Error when I try to create new contact via API

Your software
My Mautic version is: 4.4.12
My PHP version is: 7.4
My Database type and version is: 10.6.19-MariaDB-log - MariaDB Server

I have Mautic on my server, which the client would like to connect via an API to another program. When this program tries to connect to retrieve data, it works fine. However, when it tries to create new contacts via the API, it receives the response ‘The response has unexpected status code (403). Response: 403 Forbidden. Request forbidden by administrative rules.’
Any ideas what should I do to fix this error?

My API settings: screenshot-raac.itmelona.com-2024.09.11-07_49_57 - FuseBase Capture
Checked OAuth 2 credentials

Refresh the cache. And try again.
Might work, if not let’s continue.