Locate the folder, close Thunderbird then copy all the content and save in another location that may be a CD or a removable storage device (USB, Smart Card, NAS etc.).
Choose the files you want to move once you've found them. Tap Select in the upper righthand corner. Open the Files app and make sure you're in the iCloud Drive folder. Once again, you'll head to the new Files app to move your iCloud Drive files around. Some times it’s required to find command location to use it as path is not set properly to /bin or /sbin or some other folder.
