Follow the install instructions below starting on page 2. When you get to page 3 I would recommend using the https://citrixatl.sirsidynix.net link on as many computers as you can and only use the other link later if you have receipt printer issues. The Citrixatl server is faster and more secure than the Horizonweb.
Also, if you are going to set up multiple profiles on your computer, be sure to install Citrix in the profile with admin privileges (page 2 of instructions) then go to the profile that will use Horizon and enter the Citrix url and open horizon (page 3 and 4).
https://docs.google.com/document/d/13LeyK_tPIEU5_YSjXkUwdGpqtIkH0sGBDQ50Nd97PaU/edit?usp=sharing