A new feature of macOS Catalina will be the ability to share entire folders in iCloud Drive with others. Any files you place in the folder will be available to others you specify, or others with a link you want. Anyone with access to the folder can edit, add and delete files. This collaboration feature has been a part of other cloud solutions for a while, so it's nice to finally have it as part of iCloud. You can also do this with iOS 13.
Check out by using iCloud Drive shared folders in macOS Catalina on YouTube for closed captions and more options.