The ability to download files larger than 1.5 GB was added for certain file types at ArcGIS 10.4 and 10.5 respectively. At 10.4, support was added for files with a MIME type of application/zip and application/octet-stream. At 10.5, support was further added for the MIME type application/netcdf for NetCDF files.
If a problem is encountered downloading files larger than 1.5 GB on newer releases, please work with Esri Technical Support to open a new bug for the specific file type.