Google Docs is a powerful set of collaboration tools.
Often times a document that is created in a non Google format needs to be loaded to drive for sharing but needs to be kept in the original format so it can be downloaded and used in it's original format.
Setting Google Drive properties to not auto convert the document can help manage this.
In drive upload settings choose the option to confirm converting to Google Docs format.
Then when uploading the document choose not to convert.