The image describes the problem. FileMaker Cloud on AWS. After attaching a snapshot, the "Download Database" button gets the progress wheel spinning for a moment and then nothing. However, the "Download File" link works fine, so maybe just use that same link on the button?
Working on a PC/Windows 7 and the following browser versions:
Firefox Quantum 65.0 (64-bit)
Chrome Version 72.0.3626.96 (Official Build) (64-bit)