If you want to still go with API v2 – I believe you have to visit this page and follow the instructions to sign up fr a new app / api access – there seems to be a lot of hoops to jump through before you can get a client ID and access token…… if you find an easier way – please advise because I also need this.
https://anypoint.mulesoft.com/exchange/portals/nz-post-group/b8271f09-2ad8-4e1c-b6b1-322c5727d148/shippingoptions-api/
