Welcome! 
The double tap app was created to attempt to capture double taps on a switch not designed to perform that function. It is not very reliable because of the latency introduced by the cloud processing, and so itās no longer used by very many people.
The homeseer switches just came out last year, and work completely differently. Instead of trying to put a timer on the space between individual tap messages, the switch itself captures the tap pattern and then sends a single code to the hub to represent whether it was a single tap, double tap, or triple tap. This works much better.
In order for the hub to recognize that this is the method being used, you have to use the device type handler in the thread that @TN_Oldman linked to.
If you havenāt used custom code with SmartThings before, you might want to read the FAQ first so you understand what the process will be like. But itās pretty straightforward, basically you are going to copy the authorās code and paste it into your own SmartThings account. Then you will edit your device list so that the homeseer switch uses that new device type handler.
If you have any further questions, just ask in the homeseer thread, and people there will be glad to help you.