There used to be an edition of CDH called "Cloudera Express" and many people interpreted the fact that versions of CDH called "Cloudera Enterprise" required a license to mean that "Cloudera Express" was "free". I'll take your use of the term "free version" as an indication that you're making this same assumption. You can read more about the differences between Cloudera Express and Cloudera Enterprise here: Managing Licenses. Cloudera Express was discontinued by Cloudera in the Winter of 2020, please see the announcement here: Cloudera Enterprise 6.3.3 Released
…scroll down to the subsection Important Note About Cloudera Express.
I don't quite know what you're referring to when you write "secure key vault tool". Assuming you are referring to key management tools that let you create the security artifacts needed for TLS/SSL, you can read about that for 5.16.x here: How To Obtain and Deploy Keys and Certificates for TLS/SSL.
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