The idea behind IFC is that you export only the part you are responsible for. So normally the linked files are exported by the party/person creating that linked file (to avoid duplicate content in combined IFCs ).
Depending on the size of the files binding can take quite some time and might give conflicts/errors. So I would advise to export each file separately.
In the IFC export there is a setting that can help you with this.

Louis

Please mention Revit version, especially when uploading Revit files.