Modified Erd\H{o}s-Ginzburg-Ziv constants for $\mathbb{Z}_2^d$

Let $G$ be a finite abelian group written additively, and let $r$ be a multiple of its exponent. The modified Erd\H{o}s-Ginzburg-Ziv constant $\mathsf{s}_r'(G)$ is the smallest integer $s$ such that every zero-sum sequence of length $s$ over $G$ has a zero-sum subsequence of length $r$. We find exact values of $\mathsf{s}_{2k}'(\mathbb{Z}_2^d)$ for $d \leq 2k+1$.