Beeper has been working in this space for awhile - there's no way they would publish an app with a copyright violation. I assume they have a workaround for that aspect.
Just based on the wide variety of comments in that Reddit post, it sounds like there are many things that can prevent this from working. I don't know all the details of what can go wrong, but it might depend on Android version or any customizations that various manufacturers may have implemented in their Android device.
There probably isn't a single solution to getting this to work, and your problem could possibly be different than my problem.
If you figure it out, let me know. I would love to do this. I have app installed on my tablet and have the smb information entered, but it doesn't show up as Android storage like they describe.
I was actually trying to describe having the server folder mounted directly on the Android device, so the download would go straight to the server and never touch your device storage. This would be separate from using Xplore, which doesn't do what I'm thinking of. I tried mounting my NAS as smb using the app in the the below explanation, but it wasn't working.
I don't think you will be able to get anything to download to another device using any of these services. I use Unchained to get things saved to my RD area, then I run a script on my NAS to download to it (the NAS). You could maybe get something to work if you were able to mount a network drive onto your phone. Then maybe you could get the phone to download to that mounted drive, instead of to the phone's internal storage. I can access files on network devices from my Android phone and tablet using an app like Xplore, but I've never tried to see if I could have Android mount a network drive, so I am just speculating.
If I understand correctly, someone other than your ISP could see the name of the website, since it isn't encrypted. I think it would bounce through several servers that could possibly read the data.
It talks about installing with nix package manager. I've never heard of this one. Can anyone comment on how well nix would work foru Ubuntu installations? It sounds like it installs some daemon, which I haven't heard before from a package manager.
Beeper has been working in this space for awhile - there's no way they would publish an app with a copyright violation. I assume they have a workaround for that aspect.