Thanks for getting in touch. The complete version is provided for those who want to scale the piece up or down, and for people who want to add in their own custom supports. The main files that aren’t in a subfolder are the ideal ones to print this piece, in which we’ve cut it in some places to avoid those overhangs and supports.
Would you be able to attached some screenshots of the errors you’re getting? I’ve run the same piece through Cura v1.12 and not got any errors, but maybe with some images we can diagnose the problem and get it fixed.