Yes it does.
Ranged Weapon Attacks Do Damage
The item decription reads (emphasis mine):
While attuned to it, you can expend 1 charge and make a ranged weapon attack with the hammer, hurling it as if it had the thrown property with a normal range of 20 feet and a long range of 60 feet.
If you weren't attuned to it, and threw it as an improvised weapon, it would deal normal damage. So, logic would dictate that if managed to hit you by beating your armor class it when thrown as if it had the thrown property would deal normal bludgeoning damage. Using the thrown property, throwing a hammer for a ranged weapon attack would deal normal damage.
D&D Doesn't have Meaningless Rolls
By the reading that it doesn't do normal damage the effect requires both an attack roll and a saving throw. There isn't any effect in the game that requires both a attack roll and a saving throw for imparting one source of damage. This would be so out of place as to be and feel broken.
If they wanted it just to be a rare occurrence, they could have just set a easier to beat DC. They didn't, meaning the attack roll is there for something -- which would be a thrown weapon attack as the item said, and that attack would be really odd logically if getting hit by a maul of that size didn't cause you to suffer harm.
Common Language of Trigger
Then we have the way it is written. This is pretty common language for the trigger of an special effects.
If the attack hits, the hammer unleashes a thunderclap audible out to 300 feet. The target and every creature within 30 feet of it must succeed on a DC 17 Constitution saving throw or be stunned until the end of your next turn.
If the (normal thrown weapon) attack hits (before it is finished resolved by dealing hammer damage), it releases a thunder clap. Compare this language to say hunters mark or thunderous smite which read
... whenever you hit it with a weapon attack...
... you hit with a melee weapon attack during this spell’s duration, your weapon rings with thunder that is audible within 300 feet of you...
respectively. No one argues that the normal attacks of these spells don't do their normal damage. Just that the special effect of the spell (or magic weapon) is triggered when the attack lands.
In comments it was brought up that the effects of the smite spells and hunters mark was "extra damage". Which is true, that is their effect. That said, the effects of the hammer are more like the push effect part of Thunderous smite, requiring a save after the attack lands.
However, Repelling Blast Eldritch Invocation is great example that doesn't have extra or additional damage effects which makes the effect more clear (emphasis mine):
When you hit a creature with eldritch blast, you can push the creature up to 10 feet away from you in a straight line.
This doesn't negate the damage of eldritch blast or the Agonizing Blast Eldritch Invocation. The same is true for stunning strike:
When you hit another creature with a melee weapon attack, you can spend 1 ki point to attempt a stunning strike. The target must succeed on a Constitution saving throw or be Stunned until the end of your next turn.
And the Battle Master Fighter's Disarming Attack:
When you hit a creature with a weapon attack, you can expend one superiority die to attempt to disarm the target, forcing it to drop one item of your choice that it's holding. You add the superiority die to the attack's damage roll, and the target must make a Strength saving throw. On a failed save, it drops the object you choose. The object lands at its feet.
Which makes it the clearest that the rules expect the hit to already be dealing damage.