3 - Get certificate

On Mac computer, open hardware driver, choose Applications →  Utilities. Find Keychain Access, double click to open it.
On status bar of Keychain Access, choose Certificate Assistant → Request a Certificate From a Certificate Authority.

 Pop up window show:

- User Email Address – Enter your Apple Developer email.
- Common Name – Your name, group or company.
- CA Email Address – make it blank.
- Choose Saved to disk.

Click to Continue and save to Desktop. Click Done in next window.

Login to your developer account, choose Certificate, Identifiers & Profiles

Press + symbol at top right to create new cetificate.

Choose App Store and Ad Hoc. Click Continue.

Click Choose file to upload Certificate in your Mac destop, continue.

Click download to computer.

Copy to Mac destop, double click on it. Open Keychain access, if certificate has green check mark mean OK now.