You'll want to login to your UKG Ready account and open the menu in the upper left. Click on Global Setup followed by Company Setup.
Open Company Info.
Locate Company Short Name under Company Address. Paste it in Merge Link and click Submit.
Type in your UKG Ready Credentials in Merge Link and click Submit.
Open Login Config.
Navigate to API Keys and click Generate. Paste the API Key into Merge Link and click Submit!
Finally, use your UKG Ready User ID and Password to complete the linking flow.