Welcome to Apug!
This flash comes in different variants, und different brands. I do not know of a manual. But your model is selfexplanatory, for anyone with basic knowledge of classic flashes.
Your flash is SCA series 300 adapter flash. I never came across a Cullmann SCA adapter. But common are those made by Metz. They are interchangable between brands.
For your Nikon F90X
you need the Metz adapter "343" or "346 2AF" the latter in addition incorporating the AF funktion.
Set the flash at "TTL".
For your Pentax K10D
likely is no SCA adapter, but you likely may use the camera in manual mode and use the autoexposure function (set at "4" and "8") of the flash itself. Set the ISO of the camera at the flash too. For coupling you need the non-dedicated SCA 300/3000 adapter with just 1 pin at its foot.
Beware of the synch voltage of your flash, it may be too high for that camera!
In this case case you would need in addition a voltage-reducing hot-shoe adapter.