Hi Alfonso! We had this same issue with our site a bit ago. According to SG Support this is the issue:
ShotGrid team was able to identify an error stemming from a recent Mac OS update that introduced a regression within the “libcurl library” that ShotGrid Create uses to contact the ShotGrid servers. Applying an Environment variable has allowed users to bypass this error and authenticate ShotGrid Create while we wait for Apple to release a fix within an upcoming Mac OS update.
The environment variable is CURL_SSL_BACKEND=SecureTransport /Applications/Autodesk/ShotGrid\ Create.app/Contents/MacOS/ShotGrid\ Create