Apple

Generate API key (for VS integration)
To connect your IPhone to your Windows PC and start debugging and publish your Visual studio application. You need to go here to generate your key for debugging. 

 https://appstoreconnect.apple.com/access/integrations/api 

  

Set Iphone into Debug mode
Go to settings, account, scroll down to "Developer options" 

   

 This will restart the phone. You now can publish to the phone.