No Installation is required as myPOS is integrated and available as a payment method in Gombashop. You only need to activate it to set it up and use it.
To activate the myPOS Payment method go to your store's dashboard > Settings > Payments > myPOS Payment > Activate
Scroll down to find the myPOS Payment option and click on the Activate button. You can now continue to the next step with the plugin settings covered on the next page.