On a subgroup of the Burnside group $B_0(2,5)$

Let $x,y$ be generators of the universal 2-generated finite group of exponent $5$ (the $B_0(2,5)$-group). The structure of its subgroup $G=\langle xy,yx\rangle$ is investigated. It is shown that $|G|=5^{14}$ and the nilpotency class and derived length of $G$ are equal to $6$ and $3$, respectively. The lower and upper central series of $G$ are constructed. It is shown that $G$ is the largest 2-generated group of exponent $5$ and nilpotency class $6$.