The choice of the release type to use with the Zycle roller fundamentally depends on the thickness and length of the axle installed on the rear wheel of your bike.
The 9 mm quick release was the most common until the 12 mm through-shafts came on to the market. If your rear wheel has a 9 mm quick release installed, use the one included in the box with the roller.
9 mm quick release
Although if your rear wheel has a 12 mm through-shaft, you'll need to purchase a Zycle 12 mm release (See 12 mm through-shafts).
12 mm through-shafts