Deepthi Goguri covers the real value of gMSA accounts:
A Failover Cluster Instance (FCI) is a SQL Server high-availability solution where multiple servers share the same storage. If the active node fails, SQL Server automatically fails over to another node with minimal downtime.
You need to follow all the steps mentioned in the first blog post, which you can find here.
From there, Deepthi covers how to change the SQL Server service account to use a gMSA if you have FCI or other high availability setups for SQL Server.