If you found this article you are getting an Initialization failed error. I'd bet you are using a Mac. Odds are you are also running macOS Sierra. Unfortunately when you updated to the latest Apple operating system (as of this writing) it may have broken your Citrix Receiver.
As it turns out. Only Receiver 12.2 and later will work on this new Apple operating system. As above, you may have an old version. In this article, I will detail how to fix this problem and get yourself to a compatible version of Receiver.
There's a few different things you COULD do but when I drafted these steps, I decided to make it as simple as possible e.g. no changing Safari preferences to trust Receiver, no forcing a quit of Safari etc. The reason I made it as simple as possible is because most people who report this problem are likely to be remote workers who may or may not be familiar with the underlying OS.
Begin by clicking on the desktop, navigate to the menu in the top left corner of your screen and click on the Apple icon. Then click on About This Mac.
Click on Storage and then click Manage.
Click on Applications and then click the X symbol by Citrix Receiver to uninstall this old version.
Download the latest Receiver: https://www.citrix.com/go/receiver.html. When downloaded launch the .dmg file and double click Install Citrix Receiver.
Choose all defaults and continue through the install until Receiver has been installed successfully. Once the install has completed RESTART the machine. As stated earlier in this post, there are other steps you can perform and they can actually prevent needing a reboot but a reboot requires fewer steps for most.
When back on the machine after the reboot, browse to your Store. You will get prompted to trust Receiver or not, click Trust and you should now be up and running!