Specific power of attorney for purchasing immovable property

My real brother is staying in US for last 1 year and he has booked flat in Mumbai and he has given specific power of attorney to do the registration (purchasing) of that flat(NOT SALE OR TRANSFER), So in this case the SPA needs to be registered or notarized SPA will be valid? I checked on more rules of Maharashtra POA acts it is mentioned that for sale it has to be registared not for purchase. So wants to reconfirm on the same.

TO ADD THE SPA IS EXECUTED IN INDIA ONLY NOT IN US.

thanks