I am using a Blackberry Playbook OS ver. (the latest and last version there will ever be for my tablet). I installed the Storage Made Easy Cloud File Manager ver. 2.0 today and the installation went perfectly.
I was able to successfully add Google Drive as a cloud provider and am able to access it properly.

However; when I attempt to add Dropbox to my list of cloud providers, I go through the wizard until I am prompted for my email address and password used to access my Dropbox account. When I click next, the SME client attempts to authenticate with Dropbox and fails. I get:
Error (403) it seems you tried to do something we can't verify. Did you log into a different Dropbox account in a different window? Try clicking here to go back to the page you came from, or just go home.

I have confirmed that I am using the correct email address and password. I am able to log into Dropbox using that login both through the web and through my local desktop client.

I really hope I can get this working, as there doesn't seem to be a lot of choices out there for people like me still using older gear.