Why doesn't "selective sync" show as an option in the "Account" tab in "Preferences" in the tray

[tambourineman]

Why doesn't "selective sync" show as an option in the "Account" tab in "Preferences" in the tray?  I note the example in the help file has the Dropbox folder on the D:\drive (not the C:\) which is what I would want.  I have Dropbox installed on multiple computers, but have not set up a family or team account.  Is that what I need to do in order to be able sync folders on the C:\drive (from multiple PC's).  I cannot select the folder in "Backup" as the local DropBox folder is not on the C:\ drive and if I try I get an error message that Dropbox, its folder, and the desired folders are on a different drive.

[tambourineman]

If the Dropbox folder is not on the C:\ drive, how do I add folders (such as Music) that are on the C: \ drive to the list of folders list to be synced that are listed  in the "sync" tab in "preferences" using the Dropbox tray (or any other means.  The only folders available to select or deselect for syncing are ones already in the DropBox cloud.  Trying the "Backup" tab doesn't work as it produces an error that Dropbox and its folder and the desired C:\ drive folders are on different drives.  Duh!  that's exactly what I need.  I have partitioned my 1TB SSD to make C:  partition that is a convenient size to really backup (versus a Dropbox sync) in its entirety or even a file/folder by file/folder that includes the needed appdata folder.  Besides if I ever fill up my 2TB DropBox storage, that SSD would not be big enough.  do I have to install a separate syncing/mirroring program to sync the desired C: drive folders up to the Dropbox cloud?

[Mark]

I think you have Selective Sync misunderstood. 

Selective Sync is to remove folders that are sync'd to your account off the local machine only - but stay on your account. It is used to remove folders which are not needed on certain devices (due to size possibly) rather than syncing folders of choice from other directories. There is no such feature for this.