Linking Existing CRM Accounts to Existing Sharepoint Folders

Hi,

I am using CRM 2015 and Share Point, both hosted/365. I have existing Accounts, for example "Test123" and then a Share Point folder, for example "Test123". I want to "link" them so I can see my Share Point Documents under the CRM Accounts Document Tab. I have Share Point integration turned on. What is the best way to do this? Is there a document? all the documentation regarding this is for creating new Share Point folders from an Account.