versions for Ubuntu 20.04.4 and/or OpenSuSE leap 15.3

[jiulek]

Dear Sir,

Primarily, I am an opensuse user, so it would be nice to have a fgsl package specific for that (compiling from source did nor work for me).
As a contouring, I have a Kubuntu (virutal)Machine , version 20.04.4.
Unfortunately, for me the ubuntu instructions did not work.
I issue:
"
iulek@iulek-VirtualBox:/usr/local$ sudo curl http://lvserver.ugent.be/apt/xmi.packages.key | sudo apt-key add -
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 6439 100 6439 0 0 13613 0 --:--:-- --:--:-- --:--:-- 13584
OK
iulek@iulek-VirtualBox:/usr/local$
"
Then I add:
"
deb [arch=amd64] http://lvserver.ugent.be/apt/ubuntu wily stable
deb-src http://lvserver.ugent.be/apt/ubuntu wily stable
"
to /etc/apt/sources.list
(or, even if I change "wily" to "focal")
But then I get:
"
iulek@iulek-VirtualBox:/usr/local$ sudo apt-get update
Hit:1 http://br.archive.ubuntu.com/ubuntu focal InRelease
Hit:2 http://br.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:3 http://br.archive.ubuntu.com/ubuntu focal-backports InRelease
Hit:4 http://archive.canonical.com/ubuntu focal InRelease
Get:5 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Hit:6 http://lvserver.ugent.be/apt/ubuntu focal InRelease
Get:7 http://lvserver.ugent.be/apt/ubuntu wily InRelease [2.343 B]
Err:7 http://lvserver.ugent.be/apt/ubuntu wily InRelease
The following signatures were invalid: CB66CB1174623729C9A3AC4F1CA7FDC8856B2D18
Reading package lists... Done
W: GPG error: http://lvserver.ugent.be/apt/ubuntu wily InRelease: The following signatures were invalid: CB66CB1174623729C9A3AC4F1CA7FDC8856B2D18
E: The repository 'http://lvserver.ugent.be/apt/ubuntu wily InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
iulek@iulek-VirtualBox:/usr/local$
"
and so it says to me it cannot find packages libfgsl0, etc.

Is there a work around for that?
Thank you,

Jorge