Disk full - need to move Download folder

[luca.giaicheca]

Hello I have a SiteGround host, and I sell downloadable video-lessons, so I have filled my available space.

I was wondering if there's a way to edit the code in order to move the /download files to another host space.

My official site is amrita-edizioni.com, but I have another site called amrita-test.it which is almost empty.

The idea is to use amrita-test.it free space (moving files from amrita-edizioni.com) and change somewhere the code on amrita-edizioni.com so that when customers clicks to download their files in amrita-edizioni.com backend, the link leads to the files stored in amrita-test.it

Can somebody help? 

Edited February 4, 2020 by luca.giaicheca (see edit history)