I wouldn't worry too much! Turnitin is notoriously hard when judging essays. Normally at my uni, the lecturer puts out a top score of the Turnitin %s they will accept, so maybe you could ask around or double check to see if this is the case for you too.
If there isn't one or you are still concerned, emailing them is always an option and they might end up being really helpful in clarifying whether or not this is okay or giving you advice on what to do. I'd also look at what has been highlighted, normally for me Turnitin loves to highlight page numbers, references, quotes, bulletpoints and the word "and" if this is the case then that's just the system being annoying.
I hope you get it all sorted!
2nd year, Computer Science (Artificial Intelligence)