Good morning @gaila,
The 50ml scoop is the right one
The Queal powder is quite easily compressed, which can largely alter the quantity that fits in the scoop.
So I would recommend compressing the powder into the scoop (using your other hand from the outside of the bag).
This way you'll scoop the right quantity, and it also eases the process of scooping the powder into the shaker, as the powder clings quite nicely to the scoop!