1. Install  nome-shell-extension

Open terminal from system application launcher, then run command to install the extension:

sudo apt install gnome-shell-extension-arc-menu gnome-shell-extension-prefs

Once installed, search for and open “Extensions” tool. Then toggle on Arc Menu gnome shell extension

2. Install Arc Menu

go to the extension page in web browser and turn on the slider icon to install it (need to install browser extension via the link in that page).

3. Configure Arc Menu:

The new application menu by default locate in the top panel. Right-click on the icon and go to “Arc Menu Settings

In the General settings page, set “Display Arc Menu on” Ubuntu Dock to replace system default app menu.