I have taken the test and cleared the exam... The NSE7 - ADA 6.3 mock tests give you a glimpse of whats going to come but the real test was much harder than compared to these mock tests.
Nwexam covered vast subject areas and the questions were are also tricky... I would recommend to take the official course thoroughly covering all aspects of Fortinet NSE 7 - ADA 6.3 and taking these mock tests which might help...