If you want to access a file folder shared by some other user, and this user is not the Administrator or the manager of your community, you need to create a link to the shared folder. This is to give you the choice of which folders you want to access and which you don't.
Imagine that user joe has shared a folder with the name joe's documents with you. To link to the shared folder:
click on Files on the DeskNow menu
click on New link
input the username of the person that is sharing the folder (in this case, input joe) and click Next
you will be shown a list of all the shares that are available to you
select the share that you want to access (in this case, select joe's documents)
input a name for this link - or leave the default name