I’m not sure if the following approach will work on the fire tablet or not, you just need to try it and see. It would work on an Echo Dot.
One) put a physical contact sensor on the door. It sounds like you might already have this.
Two) create a virtual contact sensor to act as a proxy for the physical sensor. More about this later.
Three) create rules that determine when the virtual contact sensor gets opened, something like when the physical contact sensor is opened, but only if the SHM mode is armed. Or whatever you want the rules to be.
Four) Buy what is a music file that the echo can play that is at least 90 seconds of beeping. There are a number of different sound effects files available, so you should be able to find something. ( I just don’t remember if this works with a custom file or not.)
Five) create an Amazon routine (not a SmartThings routine) so that when the virtual contact sensor is opened, the beep file will play. i’m not sure if this will work on your fire tablet. It will definitely work on an Echo Dot.
Six) create a second Amazon routine to stop the beep from playing once the contact sensor is closed again. But remember that that doesn’t mean the physical contact sensor closed. It means whatever combination of rules you want to apply to the virtual contact sensor. It might be fine if the person leaves the door open while they go back to disarm the panel. That’s all up to you. You could mark The virtual sensor closed as soon as the alarm State Mode is changed.
Now you have all the pieces in place for what you wanted. 
The person opens the door, smartthings realizes that the door is open but the security panel is still armed, smartthings turns on the virtual sensor, echo is triggered because the virtual sensor is “open” and plays the beep file. Then whatever condition of events you have set up tell smartthings to turn the virtual sensor back to “closed” and echo stops the beeping.
It would be great if you could do this on the fire tablet you already have, I just don’t know if you can select those as a “play music” source from an Amazon routine or not. But otherwise you would need to add another echo dot to your set up.
Here’s the FAQ on the echo routines and smartthings:
There are a number of other ways to do this with other devices, so I’m sure a number of people have suggestions, but this way it’s pretty simple and pretty straightforward. Also, if it helps any, you can also mix in custom echo voice announcements.