The SalesMatik app requires iOS (iPhone Operating System) 10.0 or higher to work successfully on your iPad or iPhone.
To check your iOS version, open the 'Settings':
And then go to 'General' > 'About':
Where you will find the details of your device, including the 'Software Version':
If an update is needed, you can download it in the 'Software Update'-menu in the 'General' settings: