Upgrading an old site with spaces in the case type names and external xml files leads to difficult to resolve status messages
What happens is you get a status check message telling you the name of the file should be "Basket Weaving.xml" instead of "BasketWeaving.xml", but then when you change it you then get a status check message telling you the file is missing. It's not easy to figure out what it wants, which is that you need to remove the space from the name field in the database and then also from the filename.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information