https://wccftech.com/v1909-and-v1903-users-can-now-seek-windows-10-may-2020-update/

Microsoft has taken a rather conservative approach with the rollout of its latest Windows 10 May 2020 Update, version 2004. While the Windows maker took a measured rollout approach for the past several feature updates, this time even clicking on the "Check for updates" button isn't showing the latest version to most users.

The manual installation route is always there but then Microsoft itself advises to install the a new version only when it appears for your device through Windows Update to avoid potential compatibility issues. The company has put several safeguard holds on the May 2020 Update due to a few known issues.