The only setting you really need right on your screenshots is the first one.
System/General Setup / DNS Server Settings / DNS Servers -> type here your local Pi-hole IP Address.
The rest help, too. Should just work with the first one.
DCHP / LAN / Servers / DNS Servers -> fine too here. It's optional. If its on the main first page, it is not needed here.
DNS Forwarder / & DNS Resolver / Someone else can pitch in here. (Not needed for PiHole I think)
You last screenshot of Pi-Hole. I think that is telling PiHole where to get the info. I would setup "Cloudfared" . Look it up.
Also,
I STRONGLY recommend you set Pi-Hole on it's own PFSense interface. Do not share it in the LAN with a switch.
That way, you really command who will actually reach the Pi-hole with any custom rules (Firewall / Rules / LAN).