How can I copy a Excel docoment from a fileshare (have acces from SharePoint to it) in to a folder in SharePoint subsite
you can upload it to Documents list (Site contents/Add new app/Document Library), in this Library is drag and drop function or new document button.
Another way is to open Sharepoint Library in File Explorer and drag and drop here
This workflow action is to run on the from library
I needed a workflow action that is running in the to library and get a document from a fileshare
I don't have Nintex on fileshare
I'm sorry. You're correct, that action won't work for your situation.
I found the following article that should help you using PowerShell: