To start off, may I know if you're receiving an error message ? This will help me make sure that I can provide you with the best resolution.
Also, I'll be providing the browser troubleshooting steps again on how we can get rid of this issue.
You can start off by logging into QuickBooks using a private browser. you can use these keyboard shortcuts to open one:
Google Chrome: Ctrl + Shift + N
Mozilla Firefox: Ctrl + Shift + P
Safari: Command + Option + P
Enter the employee details from there and save it. I'd suggest clearing the main browser's cache. This removes stored cache files that cause frequently accessed sites such as QuickBooks. You can try using other supported browsers if you're getting the same thing.
Moving forward, you can visit this link if you need additional information about payroll: Get started with QuickBooks Online Payroll. This link contains more helpful articles to help you set up additional payroll services.
I'm always here if you have other questions. Have a good one.