I tried this solution and it does not work.
the devs have stopped posting builds there. they used to post bimonthly, the last post and build dates back to a year. it is critically out of date.
it is not the prefered and recomended install method for linux/ubuntu by the unity devs. they prefer we use the unity hub.
I also tried this (YouTube video by the same guy since the stackoverflow and source he links names match and since the ubuntu desktop cusomisations are exactly the same in the youtube video and the gif). This guy has got the right idea!! if a developer makes a native solution for you, you try that first.
But as you can see in his stackoverflow answer and video: things have changed even more still since the release of that launcher.
The launcher is no longer missing any dependencies pre-launch, it runs out-of-the-box on a vanilla ubuntu 19.10 with nothing else changed. That's one difference. Also it looks and behaves nothing alike visually. It's a v2 and it does have it's own quirks.
What is the method today?
I try to use the "Unity Hub" which is the recommended (and only?) method to install Unity on ubuntu.
I first have to add a license, then I have to set the download folder (which is ignored since it downloads to /tmp anyways)
Then I have to select and download a unity version :
Once the download finishes it looks like this:
if I, at this point, choose the project tab and hit "new" it still rejects me :
If I try to open the folder I find in /tmp
; "unityhub-9fbe5a20-6305-11ea-bdba-858cc54fd2fc"
with what seems like the right set of files : "Unity.tar.xz", "UnitySetup-Linux-IL2CPP-Support-for-Editor-2020.1.0a25.tar.xz", ect... then it just adds a new item named after the grandparent of that item (if I select "/tmp/unityhub-9fbe5a20-6305-11ea-bdba-858cc54fd2fc/Unity.tar.xz" it will be called "tmp", and I can no longer add another item from the entire /tmp tree because itt considers that it is the "same item". if I rename the folder and move it to "~/Documents" and open "~/Documents/unityEngine/Unity.tar.xz", the item in the list will be called "Documents") :
If I then try creating a new project, the window opens up but :
... upon clicking "create" I get a contentless error message box and from there on out the app bugs out and becomes more or less unresponsive and must be closed by force :
it seems that Unity Hub download are non-resumeable, so any problem with the network will cause the download to fail (usually without any message).
Sadly the easiest solution is to retry the download until it succeeds.
There are alternative method by manually downloading and extracting the component required but keep in mind that is is not officially supported. You can follow the following steps if you want to try downloading it manually
~/.config/UnityHub/logs/info-log.json
https://public-cdn.cloud.unity3d.com/hub/prod/releases-linux.json
I found a guide that might help you: https://docs.unity3d.com/2020.1/Documentation/Manual/InstallingUnityLinux.html
Just to summarize, you must install the setup utility, then change the permission to "make executable and run" then follow the instructions. If the above fails, try installing the missing dependencies: