The z^-2 should be z^-1 (all delay elements are unit delays), and the 0.48 should be -0.48 (coefficients from the denominator are negated on the feedback (left) side).
Also, the gain element at the top should be on the feedforward (right) side, but that doesn't matter in this case because it is unit gain (1).
Reference: https://www.sciencedirect.com/topics/engineering/digital-filter-transfer-function (See Figure 5.1. The direct-form structure.)
