Your version of Safari may be blocking the Citrix Receiver plug-in.
If you use Apple's Safari web browser on your Mac OS X device, Safari may be configured to block new plug-ins like the Citrix Receiver. To resolve, we just need to allow the Citrix Receiver plug-in in Safari.
Step 1: Open up the Safari Preferences
Click on the Safari text in the upper-right and choose Preferences...
Step 2: Open up the Website Settings for Internet Plug-Ins
Click on the Security tab and then click on Website Settings.
Step 3: Choose to Allow the Citrix Receiver Plug-in
Click on Citrix Receiver and choose to Allow Always on our citrix.ourhostedcloud.com website.
After selecting Allow Always for the Citrix Receier plug-in, you can then go back to your HarborCloud Dashboard and should be able to launch your applications successfully. If you need any further assistance, Submit a Request to our support team and we will reach out to you shortly.