From what I was reading the club is owed the 150m not Ashley. Ashley walks away with 300m cash. New owners then snap up shares from Staveley leaving her with 10 percent. The Saudis get 80 and Ruebens 10.
This 150m lark is supposed to be a way around FFP. They either pay back a club debt straight away which leaves the club able to spend a fortune as the debt is paid off and money able to be spent. If not gets paid back to club over time which enables a slower spend gradually.
Don't worry, Ashley will be gone and owed nothing. Staveley is just a broker in all this and the only thing she has done differently to that deal is come out with 10 percent.