How do you link your xfers account to your binance singapore account? I am unable to find 'Binance' under the list of addresses on Xfers digital goods wallet. Any advice?

Link the Xfers wallet from your binancesg account instead. Under settings, there will be a button next to Add Payment Method. Mine says Verified bc my Xfers wallet is already linked. Just follow the steps and it should take no more than 5 mins. (Just from personal experience, I took few tries before I managed to link them together haha so try a few times if it doesn't work the first time).

Once connected, you can just buy straight from binance, no need to transfer from xfers to binance before buying.