cover pot when cooking dumplings?

Most dumplings that are boiled are cooked with the lid off, so water can evaporate and the dumpling dough cook through.
I would guess that is also true for this recipe.
In case you are interested in the science, as well as the how-to, here is a Q-and-A about this question from a few years ago.
https://cooking.stackexchange.com/questions/62303/why-do-dumplings-float-when-they-are-ready