Hi, I'm John!
When you say the laptop is registered in Microsoft Store, do you mean it already shows under your Microsoft account devices here: https://account.microsoft.com/devices?
Also, if you are trying to manually add the laptop using the "Add device" option on that page, that feature is mainly for Microsoft Surface and other Microsoft products like Xbox. Most third-party laptops (such as Lenovo) cannot be manually added there.
Normally, a Windows laptop will automatically appear in your device list once you sign in with your Microsoft account on the device.
To help narrow down the issue:
- What exactly happens when you try to add the Lenovo laptop? Do you get an error message?
- Is your Microsoft account already signed in on the laptop under Settings > Accounts?
- Does the laptop already appear in your device list but you are trying to register it again?
Click "Add comment" to let me know.
Regards,
John J.D.