As that is a Swyama Siddha Hanuman Mantra it doesn't have for being chanted for a fixed number of Mantra Repetitions for being able to utilize it. Special worship and rituals and principles about path, sitting mat, and counting rosary are usually not suggested for chanting this Hanuman Mantra. The https://www.youtube.com/watch?v=ufkmD95y7fE&t=32s