The term "platform" in sponsoring-terms can be used in two different ways. One the one hand, a platform is a set of advertising space that a sponsor can put his messages on. That makes the German "Budesliga" a platform, as well as the Hero-IndoorSoccer-Cup, that is marketed through Sponsoo.
On the ther hand, the term "sponsoring-platform" describes the Sponsoo-Homepage itself. Speaking in digital terms, a platform is a marketplace on which sponsorship-receivers can create a profile to present themselves to advertising companys.