The CreateObject function reads the registry of the machine on which it is running to find the classid and file location of the dll of the specified class name.
So you would have had to install Excel to have the dll available and the registry entries made.
Microsoft does not support the use of workstation products like Excel and Word in a server environment. That does not mean it won't work, it's just that they won't help you with any problems resulting from using the server like a workstation and perhaps hanging it up due to single-threading etc., or asking a user who is not even there to click OK.
There are so many reasons CreateObject will fail that one could write a book about it. Most are permissions related...CreateObject needs to have permission to create objects.
In Office 2003 and beyond, Word and Excel can read and write XML-based copies of their data. Although I have not done it with Excel, I have had much success writing small programs to inject data into Word templates, directly from SQL Server queries with the 'FOR XML RAW, ELEMENTS' clause. This does not require installing the desktop Office programs on a server, a practice which is not permitted in many production shops.
You might want to revisit your strategy rather than spend time on your technical issue here!