Thanks for the feedback!
This is a strange one and I’ve not come across anything like this yet. The folder being 5+ GB is very weird, as the normal (not complete) client is smaller than that. Download on demand will only grab things as needed. I’m afraid I’m not sure what is happening here yet 
If you could file a bug report and include the launcher and recent game logs, that would be very useful in helping us reproduce. Details on how to do this are in the News Article, under the “How you can help” heading: Native Mac Client Playtest | EVE Online
Many thanks!