I came across this error while adopting the Configuration Manager 1810 (Early Update Ring)

[Completed with warning]:Verifies that the version of Microsoft SQL Server Native Client installed on the site server meets the minimum requirements to enable TLS 1.2 support. https://go.microsoft.com/fwlink/?linkid=2026746

I was apparently running an older SQL Native client version, that did not support TLS 1.2 which is required for ConfigMgr 1810.
Review your SQL versions and update to a version that supports TLS 1.2:

This link provides information about the updates that Microsoft is releasing to enable TLS 1.2 support for SQL Server 2017 on Windows, SQL Server 2016, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012, and SQL Server 2014. This article also lists supported client providers.

Download and install the correct update for your existing SQL version.
Reboot and proceed with the 1810 update.

If your looking for the ConfigMgr 1810 package to enable early update ring follow this link

The package adds your hierarchy or standalone primary to the early update ring for Update 1810 for the current branch of System Center Configuration Manager. The package is signed and bundled inside a signed self-extracting executable.

Note: The 1810 update is only applicable to 1710 and higher versions of System Center Configuration Manager