As per SEBI guidelines, it is mandatory to authorize MTF Positions on the CDSL website. 
This is because when a broker provides funding through MTF, they need to pledge the MTF  shares with CDSL. Pledging is done to protect the interest of the broker, in case a client is unable to repay the borrowed amount. 

For this, CDSL charges a one-time fee of Rs.20(+tax) and when you exit the MTF position the shares are unpledged and CDSL will charge Rs.20 (+tax) again