That's an odd one, but I would tend to trust the body of the camera rather than the instruction book. The name "Fixfocus" suggests that it would have been, well, fixed-focus, but the Belfoca isn't---you should see a focus scale on the rim of the lens and be able to turn it to focus, right?It's either a Belfoca, or a Balda Fixfocus 6x9. The front is marked with the Belfoca script on one side and "MECHANIK DRESDEN" on the other, but the back has only one sliding red port (I have no idea what it's called, feel free to educate me) where every Belfoca I've seen in pictures had two. Additionally, I have the original instruction pamphlet (I'm sure it's original, the camera has been in the family since new) Which shows a picture of the same camera, but with a Balda script on the front instead of the Belfoca script, and strangely, a label has been placed on the front cover which says "BELFOCA 6x9 cm", but when I hold the cover up to a bright light, I can see that underneath it used to say "FIXFOCUS 6x9 cm".
The Prontor-S is quite a decent shutter, I think always from the postwar era---the fact that the lens is marked in mm rather than cm also suggests postwar. If the camera was early-postwar, that might explain a certain level of disorganization in things like the relabelled user manual, but I'm just guessing.
As others have said, you can still get film for it and it should be well worth using. The older "triplet" lens design has some eccentricities that a lot of people like; this is also a camera that will make you do everything manually, which IMHO is a refreshing change of pace from auto-everything "you push the button, we'll do the rest" photography!
Really old film is worth a shot at developing. Sometimes it works astonishingly well, sometimes there's nothing left of the image, usually you get something in between. Wherever you are, there should be members local to you who can help out with this stuff.
I wouldn't be too quick to assume that the camera will need major rescuing to work well. In my experience a lot of neglected folders do just fine, especially on the faster shutter speeds (the slow-speed mechanism tends to gunk up over the years; here "slow" usually means "longer than 1/25 second"). It should be easy for someone to set you up to shoot a roll as a smoke test and see how it's working.
Enjoy it! I love these old 6x9 folders personally.