Configuration Wan port on mikrotik ipv6+dhcp+vlan+mac clone

Hello, my question is probably very simple to solve for people familiar with RouterOs, but I am a new person and am asking for help.
My ISP was provided by an ONT modem and a Kaon AR2140 router.
Soft ISP is very limited, so I am unable to enable Bridge Mode on the router.
After contacting the ISP, they informed me that I could replace their router with my own.
All I need to set is:

  1. copy the MAC address of the Kaon router
  2. set the connection as dhcp and ipv6 because this is the protocol used by the router to communicate with the modem
  3. set the vlan tag to 40

I would like to ask for help on how to do it step by step, my mikrotik is set to 0 configuration, the model is rb5009

Thank you very much in advance