I have a similar setup. Orbi RBR750 in bridge mode with Century Link fiber.
Your Orbi should have an external IP address under WAN settings
So long as your Verizon Fios router is passing everything through to the Orbi, no settings should matter on the Verizon box.
There is a Port Forwarding screen on the Orbi, and you should be able to confirm this using other websites like ismyportopen.com etc.
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