A file downloaded apparently successfully fails to accept authorization/crashes

The most likely reason for this problem is that the file has becomes corrupted or not fully downloaded and saved. This is known to be a problem where downloaded secure files are quite large and the telecommunications facilities are not very good – reports of this kind have been received from locations in Africa and some of the Pacific Islands. The solution is to find a location with better telecoms or to ask the publisher to make the file available via a different mechanism, e.g. via Dropbox or WeTransfer or SendNow etc., or on a USB stick