So managed to set it up with help of DiGi support of course.
The process was similar to TM router replacement guide as below 

https://www.blacktubi.com/review/tp-link-deco-m4-review/

But PPOE credentials are different (obviously). You will need to contact Digi for this information.
VLAN mode to 'custom' and ID is 1001. VLAN priority 0-7(up to you)

TP-Link Deco M4 is really good.

For those asking about DiGi Home Fibre reliability, surprisingly good. been using for 4 months now.
But got an issue of lost connection from the main box outside the house twice. When we ask them why they said someone disconnected it on purpose. Not sure how true is that but since its a new housing area there is a lot of cabling work going on and other vendors setting up their fibers.

Apart from that 100Mbps works like a charm.