In the Apps Script API documentation, about the POST method at the URL https://script.googleapis.com/v1/scripts/{scriptId}:run, it says that it needs the scriptId parameter, and that this is the project ID in Apps Script and that it is in Project Settings > IDs, however, I tried to make the request putting this ID in the parameter and it gave 404: NOT FOUND.
So I decided to try to use the script deployment ID as “API Executable” and it worked, so I believe there is something wrong with the documentation, can someone confirm if it happens to you too?