Thanks to some reports by Mindcraftmax, some points were corrected such as a bug in level scanning resulting in SparkShare not showing worlds to upload if scanning a corrupted level directory.
Download is automatic by starting SparkShare. As always Avast is a pain, but just be patient, Sparkshare downloads and starts the installer automatically, don't go wild clicking 10 times everywhere. It takes time because Avast is scanning. I have submitted the files and they should be unlocked soon