I looked at their website. I did not see any red flags. In fact, just the opposite. They seem focused ono teaching people how to take responsibility for themselves and that's not going to happen to any 18 year old, in any 28 day program. I like how it was created by inmates and that it has a 40 year track record.
So long as your daughter has a strong and sincere desire to change, she will. If she does not, it won't matter where she lands.
Unfortunately, I suspect she will opt for the 28 day program with her new found friends. Best case senario for an 18 year old with minimal education is competing for part time minimum wage work, $7.25 in your state. That's not going to allow her to take responsibility for herself.
Her lousy choices however, do not have to become your life sentence.That's the part you control. She is hell bent on living her life as she sees fit to do and will do so with or without your blessing.