If your content isn't stored in the cloud and is instead stored in a location that is not accessible via the internet, then you can upload your content to MediaSilo's S3 buckets, where it can then be ingested into MediaSilo.
This requires 2 calls before this method id is called. See the documentation guide for this here: Uploading Content From Your Local Storage. The API documentation for Upload can be found here: Create Upload Ticket.
You will need a project id to create an asset. Use the Get all projects endpoint to find the one you'd like to add the asset to.