This is the script for the play.
It's not an adaptation of the script into novel form. It's not a novel or a short story, it's the script for the play.
The description doesn't make that very clear but it's probably important to know before you rush into buying it.
This isn't the kind of Harry Potter book you're used to, its the script for the new play.
If that's what you're after, then wonderful! I'm sure it'll be a fantastic story and I hope you enjoy it. I'm not passing any judgement on the quality of the story, just making sure you understand that it's a play script, not a novel.