The Work Folder is a central folder that Render Boss uses to place files for operations and to communicate with the other machines on the network.
Single-Machine:
In single-machine setups, the Work Folder can really be anywhere in the machine. But in multi-machine setups over a network, the Work Folder needs to be the same in all the machines, and all the machines need to be able to have read and write permissions to it.
Note that your media and AE Project do not belong in the Work Folder, those can actually be anywhere as well. As long as all the machines have access to them.
If you are using a single machine, it can be anywhere in that machine. Example:
My Documents\Render Boss Work Folder
If you are using it on a local network, it can be any shared folder, as long as all the machines can access the folder. Example:
\\server\Shared Folder\Render Boss Work Folder
If you want to render remotely, you will need a cloud syncing service, like Dropbox, Google Drive, or Resilio Sync. And your Work Folder should be inside where the app you select to sync can see it.
If you are using Dropbox, then the Work Folder would be inside your Dropbox folder. Example:
C:\Dropbox\Render Boss Work Folder\
This would also work If you want to mix local network and remote. However, if possible, the best performance will be achieved if you share your Work Folder with your local Network also.
For Example, if Computer A has the folder C:\Dropbox\Render Boss Work Folder\. You can share that on the local network. Then you point all the other computers to
\\Computer A\Render Boss Work Folder\