I had to select the currently titular package, as Vol.4 is the only listed GooCubelets related package available in the drop-down menu.

The actual games of this package are: [GooCubelets: The Void] + [GooCubelets] + [GooCubelets: The Algoorithm]

Here's the SteamDB page for the actual package: https://steamdb.info/sub/116474/apps/

Just login there & check (manually) if you own the package (owned entries will be highlighted in green if your Steam library is synced at SteamDB) entirely or not before entering.

I don't mind partial owners entering as long as you accept the giveaway winning(s), activate it, & mark it as received.