Conversion of crdownload files to zip file format

Everything points to the fact that .crdownload files are exclusively created by Chrome web browser when a new download is initiated to reserve space for the data. Once  the download is finished, the extension is changed to the original file.

For example in case that ZIP archive is being downloaded and this download will be unexpectedly interrupted (crash) it's almost impossible to recover the ZIP archive from the .crdownload file.  Alas, in such case it is certain that you will have to download the file again.

Open CRDOWNLOAD file    Open ZIP file