Since you seem to be unable to see how my post resolves the problem you stated, let me restate it in more direct language that you might be able to understand.
The way you are trying to do it will not work:
"Control Music Player, Volume, Sounds" and "Sound Tone". The Aeotec Siren is not a music player, so the Control Music Player function will not work with the device.
Here is an example of a Basic Rule I created for my Aeotec Doorbell. The same type of rule should work for your siren.
When "Button Device" is "Pushed" (specify which button device and which specific button if the device has more than one button), Do this action "Speak Notification", on this device (select Aeotec Siren and update). Then in the "Message to Speak" field, enter the number of the alarm sound you wish to play (for example, "5" without the quotation marks if you wish to play "Westminster Chimes" when the button is pushed.)
With my doorbell, I have 30 different custom wav files set up so that various sensors trigger a specific alert. For example, when the contact switch on my back door is triggered, the Aeotec doorbell plays the sound that indicates "The back door has opened". Version 6 does not have the capability of custom tones, but you can assign different alarm/alert sounds to different triggers, not just a button device.
By the way, the Aeotec Siren 6 and the Aeotec Doorbell 6 are identical as far as the device goes. The difference is that the Aeotec doorbell comes with a separate button switch to activate the siren/doorbell. The switch can be purchased separately. If you have an Aeotec button, you should be able to pair it directly with the siren/doorbell. If you use some other button paired with your Hubitat, you will have to set up a rule to activate the sounds. If you pair it directly, it will only activate the default doorbell sound. If you use a rule, you can use any sound you wish.
I hope this helps.