Are all tracks on Soundful exclusive?

No.

Soundful's Global Tracks, Loops, and any created tracks under the Standard and Content Creator plans are non-exclusive, meaning other subscribers can also use the same sounds as you without infringing on any future songs or projects you create using that track and vice versa. This also means that the licenses for these tracks and loops will remain with Soundful.

Tracks belonging to active Music Creator Plus subscribers are under an exclusive license, meaning that only that subscriber can use those tracks in their projects. This also means that the licenses for these track can be purchased from Soundful.