Not sure what EP 4.0 has to do with it.

Doesn't matter if you install on localhost first or on live site first. Depends how/when you want to use it. There is no "problem" created by doing it "before" or "after".

If you want to install this plugin on your localhost, then you can use it to make a database backup.
If you don't, then you will need to use some other method of making a database backup.