I have a Zoho One subscription which I really like but am having money troubles and can't afford it.  The one thing I don't like about Zoho is the online resources! I find it impossible to find answers to anything.  My question is what happens when I downgrade from Zoho One. What functionality will/won't be available to me? What do I need to back up?

I use mostly: mail, Books, CRM, Projects and Sites.