Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\myDatabase.mdb;
Microsoft has not released a 64-bit version of the Jet driver. It cannot be "downloaded" to act as a 64-bit engine. download microsoft jet oledb 4.0
You likely don't need to "download" it in the traditional sense, as it has been a built-in component of the Windows operating system for years. If you are seeing an error that the provider is "not registered," it is usually due to a system architecture mismatch rather than a missing file. Why you might see "Not Registered" Provider=Microsoft