This is the Lite version of the paid app "Rainbow - Sync your between cloud services" (Rainbow - Sync your data between cloud like services). As such, you can not transfer folders, you can not share files with a link, and you can not simultaneously transfer files from different accounts to your selected folder. Also, you can not passcode protect the application.
But, the Lite version supports all cloud services that the paid version does, and you can transfer as many files you like from one account to another
You can download it from the Blackberry world at Rainbow Lite - Sync your data between cloud services - BlackBerry World