Mercury (virtual US bank account)

Hello.

Asking Amazon sellers who do not reside in USA, but selling in there.

Does anyone use Mercury as their US bank account for paying US suppliers?

Here is my situation, I am using a seller account of my friend, who registered a LLC in USA for this purpose. Since he is not selling on Amazon, and I don’t want to bother him all the time, I decided to open this Mercury account. I asked him to sign up using his LLC details. Currently we are waiting for the approval. In the meantime, it says ” Accelerate your application by connecting your business’s existing bank account. “

Which bank account should we provide? The one I’m using in my country or it should be US bank account?