Currently, you cannot share a folder, but you can share all the information regarding boards within folders and have the guests/users create individual folders. To do this, invite the subscriber into each board individually. You may drag and drop that folder into shareable boards if you're looking to share those particular boards with your clients as well.
Folders are so helpful when it comes to organizing your boards within departments and here's why!
If you have any further questions, please feel free to reach out to our customer success team right here. We are available 24/7 and happy to assist :)