-
Did the same at the weekend (all be it virtually) - booted up an old PC and Livedrive sprung into life. Nearly a TB of, varying quality and definitely shadily sourced, music from 2002-2011 on backup.
Turns out I'd been paying $3 a month for the privilege too.
Gave me an excuse to install Roon on trial, really impressed so far, though it seems to have only imported partial folders/albums into the library for some reason.
Can't help on the upload, don't really know Apple stuff these days - I take it you need to load into iTunes to then back-up into iCloud, so can't just do a file upload from the HDD once attached?
Holy shit. Lockdown spring-clean and office tidy unearthed a bunch of external hard drives, one of which has 50,000 lossless files of awesome music on. Importing to iTunes now.