Do I need a "Route" configured for route domain 0?

Hello,

If you can reach the F5 or the F5 can reach all required resources without any default gateway, it's fine, no need to add a route. Otherwise, you will need to add a default route on Network >> Route or using a tmsh command :

create /net route 0.0.0.0/0 gw 30.99.99.254

No need to take care of the route domain. If you don't specify any route domain in the route configuration it's a route used within route domain 0.