If you have the Excel file on the server then simply provide a <a> link to it, when the user clicks on it they will download it to local copy.
To allow the user to make changes to an Excel file by accessing through a web site you need server-side support for shared content editing, like SharePoint.
I have my file on OneDrive, I’m using the free plan, I simply clicked on “</> Embed” -> “Customize how this embedded workbook will appear to others”, I thought it was possible to allow the user to make changes on it through my WordPress website, but since what I understood I need a Microsoft’s paid plan to do that. Is SharePoint the easiest way?
I am not familiar with coding for WordPress, but you can share a file on OneDrive. You should be able to set permissions on a OneDrive file to allow external users to update the file but I don't know how you make it available on a WordPress page. I do the same thing with Dropbox and just post a link.
I would like to allow the user to edit and save changes on the Excel file from my WordPress website, so unfortunately I guess a link doesn't work for me. I'd need the right embed code from OneDrive.
Thank you
Oh, you actually want to display the worksheet on a web page and have users edit it right there? To do that you either need to make sure your user have web-based Excel or you basically need to write your own version of Excel. There is no easy way to do this.