@El_Colorino great you got it working.
@dwrice0 thanks for all those screenshots - awesome! And you’re right, you shouldn’t need to change the general firewall settings if you’ve used the wizard, as it will setup wlan to be accept all on that particular zone. With the WGB terminology (Cisco’s words for this, AFAIK), my apologies for the confusion. We had/have the problem that everyone talks about this differently (e.g. bridge, WDS, 4 address mode, extender, mesh (!)), and we’ve struggled to get people to read long explanations, so we tried to go with ‘here is a simple description of the effect of what will happen’.
By the way, it should be possible to do most of the changes/see most of the stuff on the Quick Config page as well. Ok, I’m personally attached to this one 
(I wrote the Quick Config page, and I just want people to like it!).
i.e. after configuring as ‘get an IP on your existing network’, you should see:
As @dwrice0 said, it’s put wan and wlan0 on the ‘wlan’ network (implicitly creating a bridge). If you want to bridge more/different things, it’s a matter of changing your ‘Network Interfaces’ section to move ethernet ports around, or your wireless sections to move them on wlan.
Another way of understanding the changes the wizard has made is to look at the uci config files in /etc/config/wireless and /etc/config/network, which the Quick Config page should correspond to quite closely.
Finally, since I can’t help myself offering yet more answers, if you really just want a setup like an Extender @El_Colorino, you could switch it to extender mode then just change the mode of the HaLow interface to AP (WDS) and everything will be bridged on the lan network. Just plug the Extender into your router so it will get an IP and you can get to the web interface.