The name of the file within the zip is using a dash instead of an underscore and causing a name error in loading the mod.
expected CollectDroppedItemsHotkey_0.16.0
received CollectDroppedItemsHotkey-0.16.0
just a simple fix of changing the file name.

Odd - no issues here with it as it is.

The zip file is created from the github releases zip download, and that controls the separator between the mod name and version, so I'd rather not have to manually rename it each time I release an update.

Are you unzipping the mod? Works fine with a zipped mod - tested on a fresh install of 0.16.7 and installed via the built-in mod interface.