When models are uploaded, they are posistioned in the printer according to the orientation given to them by the designer. Printer sizes are given in the back end, under "Materials/Printers" The sizes are understood as length (x) x depth (y) x height (z), looking from the operator's point of view.
If an oblong object is loaded, and the printer has an oblong form, it may so happen that the model doesn't fit at first glance. Let's say
the printer has an x of 200, an y of 150, and a z of 150,
the model has an x of 100, an y of 160 and an z of 100:
It will not fit on the y axis (150<160).
If, however, the model is twisted two times by 45 degrees (=90 degrees) around the z axis, everthing will fit: 200>160, 150>100, 150>100, and a quote can be generated.
In fact a new model has been created, so it gets a new name ending, which is made up of the movements and the axes involved _z-90 in this case.