How is it at infinity? And are the images aligned? If it's just a distance setting, that's not too difficult. And it might be that the actual focus at the film plane is in agreement with the rangefinder, but the number scale is off.
And try for brighter light? I've never found the Zeiss prism system very good in dim light.
Are the bellows good? Have you shot any film yet? Calibrating the focus and rangefinder system is a tedious project, but if the camera is in good shape it can be worth going through since there are so many mediocre and damaged cameras out there of this type. Do a search on aligning Zeiss rangefinder prism or such to get a feel for what is involved and if you want to give it a go. If not, and it is flawed, return it, I guess.