I'm hoping you weren't manually copying that app to the home screen of all of your devices previously as that would have been a big waste of time. Enterprise Home Screen is configured via an XML file that is placed in the /enterprise/usr directory on Zebra devices. You can configure a single device to your specifications, export that XML file, and then distribute it to all of the devices via a SOTI Package or File Sync rule so that they can all be managed consistently. This is why you have a capable EMM like SOTI in the first place.
Now, if you already are performing that process listed out above but are having trouble adding one app to the home screen to create a baseline XML then that shouldnt be a problem because you can manually modify the XML file itself. In fact, I almost always just manually edit the XML file itself at this point. All you'll need is the Android Bundle/Package ID for the Citrix app which you can pull from the device's Application tab in the SOTI server. You can then plug that information into the XML file and deploy it to the devices: