Creating a Payment Plugin for J2Store using CardStream

We currently have a Joomla website using J2Store and require a new payment plugin to allow us to take payments using our new card supplier CardStream.

The card supplier is called Card Stream (open payment network) and this is there developer section: https://cardstream.com/developer/integrations/
If you scroll a little you will see guides, plug-ins etc. I have also included the link to there PDF too https://support.cardstream.com/hc/en-gb/articles/360012171277-Gateway-Integration-Guide-

J2 Store Payment Plugin Integration Guide: https://docs.j2store.org/developer-guide/payment-plugin

We are going to be using the Offsite/Hosted Page option and not the Direct option.

Please take time to look through guides and see if this is something you are able to do quickly,

Any more info required please let me know