The place that they went to for the ransom exchange was on the outskirts of the city. It was an area in the slum where poor people lived, and crime was rampant.
The two of them got to the location in the ransom letter. But they didn't go there with the money that they were asked to bring. They went there for two things.
Their first and most important goal is to free the kidnapped disciple. They achieved this easily when the kidnappers brought him for the exchange.
The kidnappers weren't afraid of Leroy and Princess because they thought they were at the peak of the second mortal coil. They didn't know that the people they were messing with were from the Blood Skull sect because the kidnapped boy didn't tell them this.
The kidnapped boy didn't tell them their background because Arthur had instructed him to be secretive about their identity and purpose. So far from being afraid, the kidnappers planned to take the ransom money and kidnap or kill Leroy and Princess, too.
