Hello pat_hayes,
Thank you for reaching out in Apple Support Communities. We understand you're unable to download an app on your iPhone, due to an error message that appears. We'll be happy to help and point you in the right direction.
You mentioned that your iPhone is a work device. Is it supervised by a company or an educational institution? If so, that might be the reason of why you're unable to download an app. To verify that, you'll want to check and see if there's a profile installed for mobile device management (MDM). Here is detailed information about mobile devilment management on an iPhone: MDM overview for Apple devices
To see if there'a configuration profile installed, you can go to Settings > General > Profiles & Device Management. That information is outlined here: Install or remove configuration profiles on iPhone
Please keep us posted with an update.
Kind regards.