In which case Peplink’s high availability function seems not to be the appropriate architecture for your use case.
As for the diagram from the Peplink documentation:
I see an active master and an inactive slave (as indicated by the grayed-out communication lines, the grayed-out slave and its labels and the context of the diagram in the Peplink documentation). You may also note that VRRP is on the LAN side only (as explained by @padaco-daniel )
But that is neither here nor there, w.r.t. the clarity of the documentation. I get it that you understood it to mean something other than what was intended. Since Peplink folks are participating in the forum I expect they’ll take notes as warranted.
Good luck.
Z