If you selected Browser at first and you want to change to Receiver you have to download the Citrix Receiver. Please use this link http://receiver.citrix.com.
Cloudalize can be accessed from any HTML5 browser. For extended functionality (eg. multiple screens) and best user experience, we recommend installing the Citrix Receiver and selecting Receiver.
As an admin you can change the set connection preference for the company and lock this if you do not wish your users to modify this:
If the admin didn't lock this, a user can change the way they connect to the desktop too. Select your avatar at the top right. Choose Profile. The selected connection preference will make sure that every time you launch your desktop, you will connect either via Receiver or via Browser.