2 of us to be in Hong Kong for 3 days (Fri - Mon). What is the best travel pass for local travel plus roundtrip on the Airport express?

Is it better to buy in advance online? (this is after Oct 1st)

Did some searching - looks like there is such a pass.


Airport Express Travel Pass - 2 Airport Express Ride
HK$300.0
HK$285.0 online

Each pack includes:

•2 designated journeys on the Airport Express (excluding travel between Airport and AsiaWorld-Expo stations) plus 3 consecutive days of unlimited travel on MTR, Light Rail and MTR Bus (Northwest New Territories)* (except additional travel on the Airport Express, East Rail Line First Class, and travel to/from Lo Wu or Lok Ma Chau stations)
•A refund of HK$50 upon returning the Pass
•Earn 150 Asia Miles for online ticket purchase


https://www.paydollar.com/b2c2/AELCo...000&itemid=214

What are Asia Miles?