Go for simple and cost effective solution.

Create a Global Space in Network (Global Network Folder)

Whenever user try to send a file create a new file in Global Network location and pass the path link. In order to avoid overriding file name you should consider using naming format like

File_DDMMYYYYHHMMSS.zip

You won't find good solution than this, since if you want to make this project live and want to allow even Internet users to share their files, they can able to by applying proper security steps.