Is it easy to install ms office 365 where nothing goes to the cloud?

It is

Yes, of course.
You can set things up so that all documents and other items are saved locally.

- Brad -

Don,

          Not much to add to what you've already been told other than to mention that the use of OneDrive cloud storage predates Office 365.  I still get occasional nags and I use Office 2016.

          For in-depth questions regarding Microsoft Office (regardless of what version) consider joining the Microsoft Office Accessibility Discussion Group:

• Post: office-accessibility@groups.io
• Subscribe: office-accessibility+subscribe@groups.io
• Unsubscribe: office-accessibility+unsubscribe@groups.io
• Group Owner: office-accessibility+owner@groups.io
• Help: office-accessibility+help@groups.io

--

Brian - Windows 10 Pro, 64-Bit, Version 2004, Build 19041
The purpose of education is not to validate ignorance but to overcome it. 
       ~ Lawrence Krauss