From the paper:
The dataset contains six colon cancer subtypes: class 1 = CINImmune-Down (116 samples), class 2 = dMMR (104 samples), class 3 = KRASm (75 samples), class 4 = CSC (59 samples), class 5 = CINWntUp (152 samples), and class 6 = CINnormL (60 samples).
CINWntUp and CINnormL are therefore two classes of colon cancer. You are correct, CIN is for chromosomal instability; WntUp refers to upregulation of Wnt, a signalling pathway involved in some cancers and named for a Wingless/Integrated phenotype in fruit flies and the homologous gene in vertebrates. normL stands for "normal-like."
See the original paper describing these classes:
Marisa, L., de Reyniès, A., Duval, A., Selves, J., Gaub, M. P., Vescovo, L., ... & Kirzin, S. (2013). Gene expression classification of colon cancer into molecular subtypes: characterization, validation, and prognostic value. PLoS medicine, 10(5), e1001453.