Did remote access work for you before?
Remote access can be tricky because there’s so many players involved. Common troubleshooting steps are documented here → The Basics of Remote Access Troubleshooting
To the best of my knowledge, Plex doesn’t advertise an option to download media from their online media sources. IIRC this is due to licensing limitations.
There’s quite a number of Plex Pass features making it worth for many. Most of them are however related to features of personal Plex Media Server setups or client apps.
https://support.plex.tv/articles/201751006-plex-pass-feature-overview/
You could reach out to https://www.plex.tv/contact/?option=plex-pass-billing
