I just took a quick look at this widget and the reason this is failing is because of the case sensitive nature of our Linux cloud servers. On your workstation it doesn't matter if folder/file references are written in different case. But in the cloud all widget and library references are case sensitive.
The widget is referring using the following require statements:
location: '../../widgets/ClockPickerForMendix/lib',
but the name of the folder is: ClockPickerforMendix (note the lower case F)
I would recommend validating all paths in the widget and confirming the naming of all items. If the paths are written with the correct case I would expect the widget to work.