I have some experience with TSDZ2 mid motor, that is in many way similar to Bafang. They mount to standard BSA thread BB, so you need to convert yours to that. But you can't go with a normal USA/BSA adapter, because the motor leans close to the BB, that means the thread must be off-center leaning to one side. That is exactly what an off-center adapter provides you with. Luckily they are often used on tandems and other bikes sometimes too, to be able to tighten the chain.