1. If you experience the message -  Firefox: You have chosen to open: launch.ica which is: Citrix ICA Client (2.2 KB) What should Firefox do with this file?, click the drop-down box and select Citrix Connection Manager. Mark the checkbox Do this automatically for files like this from now on in order to store this decision and click OK. The Hosted application should launch in a few seconds, or you may need to click the Blackbaud Hosting Services application once more. 
  2. If you experience the Blackbaud Hosting Services application not launching and do not receive the above prompt, in Firefox: 
  • Click the Open Menu icon (three horizontal lines icon under the "red X", upper right of application) 
  • Select Options (Cog wheel icon)
  • Select Applications on the left navigation panel 
  • Find Citrix ICA Client and click the drop-down box to the right. Select Citrix Connection Manager. 
  • Launch your Blackbaud Hosting Services application 
Video walk-through of above steps here 

If using a MAC, uninstall Citrix Receiver 12.5 and install Citrix Receiver 12.4. The uninstaller and installer package file can be found here: Citrix Version 12.4 for Mac