Hello JW7630,
You can find details on how to configure a splash page and redirect here https://documentation.meraki.com/Go/Meraki_Go_-_WiFi_Access_Point_Feature_Details#Access_Control
Meshing will automatically configure. Claim the Access Point through the app, then plug it into power, but don't connect via Ethernet. Of course you have to already have at least 1 Access Point already turned on and connected via ethernet to your router.
Meraki Go automatically uses both 2.4 and 5 GHz for a configured network/SSID.
Lee