For reasons unknown, aMule, all-platform eMule P2P Client, is not included in Ubuntu 20.04 main repository.

While it’s available in previous Ubuntu repositories as well as the next Ubuntu 20.04 main repository, you can manually download the package and dependencies from Ubuntu 18.04 and install them manually in Ubuntu 20.04.

1.) Click download the amule package:

amule .deb

2.) Click download amule-common package:

amule-common .deb

3.) Click download amule-utils-gui package (optional):

amule-utils-gui .deb

4.) Finally download the libwxgtk3.0-0v5 package:

libwxgtk3.0-0v5 .deb

When downloading processes finished, open terminal (Ctrl+Alt+T) from system applications menu and run single command to install them:

sudo apt install ~/Downloads/amule*.deb ~/Downloads/libwxgtk*.deb

Once installed, launch the client from your system application menu and enjoy!

(Optional) To remove the amule package as well as dependencies, run command:

sudo apt remove --autoremove amule