This message is received due to changes in iOS 11 that make it incompatible with 32-bit apps. The Raiser's Edge Mobile Event Management app is currently being rebuilt in accordance with the newest iOS guidelines.
In order to use the Mobile Event Management app before the new version is available, please wait to upgrade iOS beyond 10.3.3. This article will be updated when the new app is available.
NOTE: Just until the updated app version is released... If other users will use the app, such as volunteers or other staff members, or do not normally use it and/or may be helping on the day(s) of an event, be sure to communicate to them to NOT follow / allow any iOS update prompts if received.