Today I installed Kubuntu 21 (minimal install) to virtual machine for some cqrlog install testing.

It looks like Kubuntu is using GTK3. It also had some other problems with my keyboard layout. While my keyboard works with Fedora, Mint and Ubuntu with latest Kubuntu there was no way to find suitable layout for my mini keyboard (from warehouse truck) that has no numerical keys part at all.

Anyway once install was completed I made VM clone from installation to get new fresh Kubuntu install again within two minutes. No waiting to install procedure complete again if something goes wrong.

Then it was time to start cqrlog install.
I decided to do it without package using the tar file from bottom of download page named "Complete application directory for other distributions"

I opened command console and then:
changed to /tmp directory
cd /tmp

First I installed dependencies needed. Installing this list will install also some additional packages that are needed. How ever just accept them all to be installed:
sudo apt install mariadb-common mariadb-server mariadb-client libmariadb-dev-compat libmariadb-dev libhamlib-utils libssl-dev trustedqsl libgtk2.0-0 libgtk2.0-bin libgtk2.0-common

After that was done I downloaded cqrlog from downalod page link using wget that is included in Kubuntu minimal install:
wget https://github.com/ok2cqr/cqrlog/releases/download/v2.5.2/cqrlog_2.5.2_a...

Then extracted the file (that installs cqrlog):
sudo tar -vxf cqrlog_2.5.2_amd64.tar.gz --strip-components=1 -C /

Finally started kmenueditor to add cqrlog to start menu:
/usr/bin/kmenuedit

With kmenuedit first added a new submenu (submenu button) named "HamRadio"

Once it is added to left side submenu list go through all other submenus. It might be that you will find cqrlog under "internet" subfolder. I am not sure did it appear there after rebooting as I did not find it right after issuing the "sudo tar" command and did not want to start again with clean Kubuntu just for checking that.
Maybe it is good way to log out and back, or even restart PC, at this point to let system to find cqrlog menu item (it is copied there while executing the "sudo tar" command).

If it is there drag and drop ti to your submenu "HamRadio" and close kmenuedit.

If you can not find cqrlog then select HamRadio and then press "new item" (left side of new submenu button).
give name "cqrlog" and press ok. Then press bigger square at right edge (right side of given name). Icon selector opens. Select "Other icons" and you will see cqrlog icon. Choose that.
You can add description and comment if you like. (they are not required)
for command write "/usr/bin/cqrlog" (without quotes)
If your menu item is not at right menu folder you can drag and drop it there.
Then close kmenuedit and start cqrlog from start menu.