Darwin SDK -- The maximum size that can be uploaded is 10GB. Files larger than ~2GB can be processed by analyze_data() only. Model creation might not be successful for files larger than ~2GB until Big Data is fully supported. Analyze_data() is the only method that supports Big Data.
Darwin API -- Currently the maximum file size that can be uploaded is 500 MB.
Darwin User Interface -- The Darwin UI is still in Beta, and currently only supports file uploads of 50 MB or smaller.