Adding an additional or shared mailbox from the same Exchange organization to Outlook

I’ve been granted access to a shared mailbox on our Exchange sever. For this, I’ve been given the name and email address of the mailbox but I didn’t get a password for it.

When I try to add the account, Outlook already resolves my current name and email address. While I can change this, it then also asks for the password which I don’t have.

How am I supposed to access this mailbox?