Windows 10 2004 (May 2020 Update) has officially reached the end of support on December 14, 2021. This applies to all editions of the OS, including Windows 10 Home, Pro, Enterprise, Education, and even Windows Server version 2004.
Although you can technically continue to use version 2004 since Microsoft no longer offers support for this release, computers running this version will stop receiving security and quality updates, and you can no longer contact the company for support.
If you have a device still using the May 2020 Update, the system will soon upgrade automatically to the next supported version, which in this case will be version 20H2 (October 2020 Update). However, you can always upgrade manually to the latest version, which at the time of this writing is version 21H2.
To upgrade manually, you should be able to complete the task from Settings > Update & Security > Windows Update, click the Check for updates button, and then click the Download and install option for the newer version available on your device.
Once the feature update is applied to the device, you will need to restart to complete the installation. The process should not take a long time, since version 20H2 and higher releases are small updates with only a few minor improvements and features, and the installation does not require full reinstallation.