In order set up push notifications for the iOS mobile devices, please, follow next steps:
Step 1: Click on Notifications button
Step 2: Put a check mark near Apple option and the press Configure
Then press on I don't know how to create a Certificate, Private Key and Provisioning file, or I don't have a Mac computer and click Generate New Certificate Signing Request (CSR)
Step 3: Download generated certificated and go to apple.developer. In the opened Developer pannel go to Identifiers
Step 4: Choose needed Apple ID and click on Edit button
Step 5: Check Push notifications, push Create certificate in Production SSL Certificate
Step 6: Press Continue
Step 7: Upload the certificate you have downloaded from your reseller site and click Generate
Step 8: Dowload new certificate and click Done
Step 9: Go back to your reseller site and upload the Apple Production certificate
Step 10: In popup window press Yes then choose Apple iTunes Store.
Note: you would need to resubmit a new build to iTunes App Store after setting push-notifications.