I had a look at the example "Download Cache Tile (Beta)" and the program never starts the download of the cache tile, no signals were emitted from the tilecachetask and the progress bar wasn't displayed.
Trying to check this behavior, I did a small program based on this example and I got the same result, the TileCacheTask did not download the tiles. Then I modified the initialization of the TileCacheTask, adding an "userCredentials" with the info of my ESRI Global Account and later the info of my Developer Account, in both cases the TileCacheTask emitted the signal "tileCacheError" showing an "Invalid token" error and later the TileCacheStatus signal. How can I solve this problem?
Thank you for your interest for ArcGIS Runtime SDK for Qt. We will be releasing a new version of the SDK shortly that should address this issue. Sorry for the inconvenience that it has caused you.