Just because they did not call the police to the store doesn't mean they won't submit the case to them later.
The letter asking for money is not a scam, it's considered compensation for having to deal with your crime. It helps pay for things like video recordings, LP staff to catch and prosecute offenders, lost merchandise, etc etc. As to whether you pay it or not, that's up to you. But look at is this way, if you were the store and caught several shoplifters and half paid the demand letter and the other half didn't pay, who would you be more inclined to call the police on? The ones who paid or the ones who didn't? There is no promise that if you pay you won't get a call from the police, so you have to decide if it's worth it to you.
Yes, you should be very worried about a criminal record from this, it can make your future employment possibilities much more difficult for many years.
This is not legal advice, just what I would consider doing at this point. Pay the civil demand letter and also contact a lawyer to be ready if you do get charges. At least meet with a couple of lawyers to you have someone you can call when/if the police are suddenly knocking on your door.

