Well Matt, if you are on the free MoodleCloud site then the links I gave you before will give you the details. You only have 200 MB space because you are expected to make links to your documents from other places online like Google drive, Dropbox or YouTube - and you can still do that if you want. You can get rid of your 200 MB by putting some of your files somewhere else and then you can keep the free site. But if you prefer to have more storage space then, according to the MoodleCloud rules you will have to pay.
I just want to add by the way that Moodle software IS actually entirely free and open source to anyone who wants it and is able to install it on a server. You do still have to pay for the hosting. MoodleCLoud is just a quick and easy (official) way of having this done for you so you can focus on the teaching.