Do I need to link my HSBC Revolution Credit Card to google pay in order to earn 4MPD rewards or I can just use the physical card?

Both physical card or PayWave is okay, including online, just make sure it is under the white list mcc

You can use the physical card to make a contactless transaction, e.g. via PayWave. So long as the merchant does not fall under the excluded list, you will get 10X Points, equivalent to 4 miles per dollar.