@Terri, the ST button’s default driver doesn’t include the “double” in button’s supported attribute value. You can grab SmartThings’ device driver for the SmartThings SmartSense button from the link below, rename the device handler and add one line attribute "button", "string" as shown in the screenshot, and change the device’s type to this updated device handler.
Edit the device in SmartThings IDE site to change the type to this updated device handler.
Then, reauthorize this device to SharpTools in the user page again. Now when using the button as the trigger, you can just type double, pushed, or held as you need.
Let me know if you have any questions.