Since you were not taken into custody or officially arrested by law enforcement, you don't have to worry about having a criminal record. It appears to be a record only for the store. This can be used in the future if  you are caught shoplifting again in that same store.

Usually, you will have a criminal record when you are actually convicted of a crime. For purposes of job applications, you are usually asked about official arrests and convictions. You were lucky this time so don't do it again. You are too young to have a criminal record. With a record for theft, you will have very limited employment opportunities. This is a "mistake" that will follow you for a long time.