I would start my investigation:
1) With checking the ground glass. Is it mounted correctly? Is the grain side facing the lens?
Otherwise turn it over.
2) A next step would be to check the position of the front part. On my Agfa Standard it has a position where it snaps into place. I have to pull the front part the last part.
Try moving the front part back and forth and see if the focus becomes better. The click position is perhaps not optimal and should be changed?
3) Try increasing the aperture number (reducing the aperture opening) to increase the depth of field in good light. Do you get focus now?
3) My last check would be the front lens. Could you install it in some other position?
If everything is OK, I am out of ideas.
But as I wrote, the lens is not to be compared with modern lenses. It does not give as sharp pictures as my Leica lenses, especially at low aperture numbers. Remember it is only a two glass lens. I think Leica Elmars (50/2,8) has five! In fact I was a little disappointed with the sharpness. But the camera gives you a soft retro look which I like! And I enjoy using old folders!