Clicky freehub generally means the pawls are engaging snappily. This is good in that if they are slow to engage and aren’t fully engaged when torque is applied, the pawls or ratchet ring can get damaged. (Low temps can slow pawl engagement.) Pedaling trainers when standing can sometime get clunky, which exposes the pawls to disengaging and reengaging at high torque against the inertia of the flywheel, so it’s good to have snappy pawl engagement. Some designs are louder than others, and it’s usually best to use the freehub lube specified by the manufacturer. FWIW, I use 90 weight gear oil on my trainer’s pawls.