Windows 10 May 2020 Update started rolling out to mainstream customers on May 27, but the update is not available for everyone. Microsoft said that they are throttling the rollout of the update to reduce compatibility issues. Dell and Lenovo have published their own documentation to confirm a list of systems tested for the update. Lenovo recommends users to roll back to the older version of Windows 10 such as the November 2019 Update. If your device is listed as compatible and there are no known upgrade block, you should be able to download and install Windows 10 version 2004.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10-2004-dell-and-lenovo-publish-list-of-compatible-devices/