Does she have to apply for a Macau visa before she enters into Macau or can she come there without any?

Dear Sirs / Madams,
My Mother in law (My relative) is coming to Hong Kong for a visit. He have just got the Hong Kong visa approved for her and have it in hand. My question to you -

If my relative as mentioned above wants to visit Macau for the day only ! And she is holding a Sri lankan passport -
If she has to apply for it- Can she do it from here in Hong Kong when she arrives ?
How long will it take ?

Awaiting for your prompt and urgent reply.
Thanks and best regards
Hitesh Harjani
My email add is : hitesh_harjanihotmail.com