Metahumans Plugin for 5.1.0 ?

Hello! I do everything according to this lesson: Unreal Engine 5 | Enzo Behind the Scenes | Part 9: Creating the Metahuman Body Morph in Maya - YouTube
When I get to “merge vertices” at 10:03 and send the model after Zbrush back to UE5.1, the model loads with errors, and the UE crashes, but if I send the model without “merge vertices” then everything turns out fine, morphs in UE work, but at the same time, gaps are obtained on the character’s body at the joints, does anyone know how to solve this problem?