You can’t attach things to the workbench because it is just a view into the shop orders showing the next available operation per shop order organized based on the filter.  The attachment needs to be further up the line connected to the inventory part, or the shop order, or the shop order work guidelines depending on what it is you are trying to make available.  Connecting to the routing operations would be for specific instructions for that operation, but drawings for example would best be connected to the inventory part and then transformed via object connection transformations to the point you want to view them at the workbench level.  There are a few posts on the community on this subject, but you won’t find a direct solution to the way you’ve phrased your question because the connection to the workbench doesn’t work in that manner.

We use Aurena - App 10 and on the workbench you should see a paperclip. After pressing the paperclip you can attach existing, create new or create from template. I do not see a way to do this from IEE.