We have our Help Center Article on how to get a UKG Pro account linked. Here are some common error that we see for this particular integration:
The Account will not Link or says Relink Needed:
Troubleshooting Tip 1: The end user entered the incorrect API Key
Solution: The API Key is the Customer API Key found in Step 1.2 of our guide.
Troubleshooting Tip 2: The Username and Password are for the Service Account created NOT the login credentials, as shown in Step 2.6 of our guide.
Troubleshooting Tip 3: The UKG subdomain is NOT the URL subdomain. This value is found in Web Services. To learn more go to Step 3.2 in our guide.
Troubleshooting Tip 4: The Service Account must have access to Employee Person Details to authenticate with Merge Link, as shown in Step 2.4
Null Data or 403 Error Codes:
Troubleshooting Tip: Ensure the Service Account has the correct permissions for the data you requested.
For example, if you wanted to have a pay details in the Employment object, check off the Employee Compensation Details.