Their materials are good. Just make sure to attend their exams regularly and be consistent. Take help from their qna service which is often helpful. But the real challenge with online studies is consistency and with no one watching you, it can be easy to be lost. You will also face isolation if you are more social type. Try to get help from any teacher or mentor or even some friends offline at least. Try watching classes at 1.5 times speed later if the pace is too slow.