Change open a file link in app not download

I have a SPO site that has a number of libraries containing links to [mainly] excel files.  These files are hosted on our own servers and is available from an IIS website.

Although the process is working I cannot seem to access the file directly ie open in excel.  It will always go to download.  I've changed all the sharepoint setting to open in App.  I've tried the Adding  ?Web=1 to the end of the url but cannot get the link to open directly in the app.

example of a link:

https://website.company.com/folder/excel.xlsx