Hi, what kind of phone do you have? Apple does not support XPlane 10 Mobile. If you have an Android phone, you may want to check your storage, as XPlane 10 takes over 1GB of phone storage. Deleting unwanted apps and/or photos will definitely free up more memory for XPlane 10 to run on. However, the newest update for XPlane 10 Mobile (10.8.0) is said to have a number of problems, so if you free up enough storage to get it, I'd recommend waiting until the next update arrives. Best of luck and happy flying!
TwelveYearOldPilot