I've known about this project for about 2 years now, but was reminded of it by a friend and decided to start contributing again on my Windows 10 laptop (AMD) a week ago (Thursday night). I also have a notebook with an intel Atom that my brother gave me because he didn't know what to do with it and so I told him to install Lubuntu (since I'm more used to Ubuntu because I use a VM for some assignments that I have at my university). I've been trying all day to make this work. When I try using Science United as an account manager with the version from the package manager (7.9.3), as BOINC's site recommended, it says:

https://scienceunited.org/: Notice from BOINC
Message from account manager: Science United requires a newer version of BOINC. Please install the current version from
https://boinc.berkeley.edu/download.php

This is the same site that I looked up the first time.
Where should I look for a newer version that Science United actually accepts?
I'm also trying to figure out how to add my Android phone to Science United. I added SU as a project. Did I do this right, or should I just wait until next client release?

You were mislead by Science United's message.
The URL should be https://scienceunited.org/download.php
There's a link to that page on the front page of SU's website when you're logged in.

I think adding SU as a project on Android is the only option for now.

Both BOINC and SU give you a shell script that downloads an older version of BOINC (not even VirtualBox). After running it, the terminal tells you to run the run_manager file. When I run that it tells me that an object that has a name that starts with libwx is missing (I don't remember the full name because that's one of the things I did by myself, yesterday and I just want another solution).

Also, I added Science United as a project on the Android version and what it does is it counts down 24 hours, makes a connection request and then restarts (in other words, it doesn't work/doesn't receive any new tasks).

Thank you for your determination and information. This situation needs to be addressed and I'm sure it's on someone's to do list.

For my boinc installations on ubuntu hosts I use https://launchpad.net/~costamagnagianfranco/+archive/ubuntu/boinc
I suppose for lubuntu it will work as well.

That did the job, thanks!

Just wanted to add that this worked for me. The script didn't work just the same as the OP. Adding the PPA allowed me to get an updated version of Boinc.