Packages and installation files are available at Releases page. Alternatively you can install the app with one of the following methods.

On Windows you can install Chocolatey package.

On OS X you can use Homebrew to install the app.

brew cask install copyq

On Ubuntu set up the official repository and install the app from terminal.

sudo apt install software-properties-common python-software-properties
sudo add-apt-repository ppa:hluk/copyq
sudo apt update
sudo apt install copyq