You only list Ubuntu 22.04 and 24.04. Does either of these work on 20.04? If not could you compile one up? I use 20.04 for various compatability reasons and have a Ubuntu Pro account so it should be good for some years yet. 
This is a user to user forum. You must address your questions regarding to UltraEdit for Linux v2023.0.0.21 with an email to support of UltraEdit, Inc. or using the technical support form.
There can be tried the installation on Ubuntu 20.4 with the GZip compressed TAR package for Ubuntu 22.04. UltraEdit for Linux v2023.0.0.21 cannot be used on Ubuntu 20.04 if uex does not run after extraction and there are no Ubuntu 20.04 backports of the libraries in the version required by UEX v2023.0. There is the old power tip: How to use the UltraEdit for Linux tar package? It may help on the installation without a suitable DEB package.
There can be tried the installation on Ubuntu 20.4 with the GZip compressed TAR package for Ubuntu 22.04. UltraEdit for Linux v2023.0.0.21 cannot be used on Ubuntu 20.04 if uex does not run after extraction and there are no Ubuntu 20.04 backports of the libraries in the version required by UEX v2023.0. There is the old power tip: How to use the UltraEdit for Linux tar package? It may help on the installation without a suitable DEB package.
Best regards from an UC/UE/UES for Windows user from Austria
