Flyback transformer one winding primary side and two winding secondary side
The ratio is 10:1 for one low voltage winding (or two in parallel) to the high voltage winding. (I'll avoid using "primary"/"secondary" since your definition is the opposite of the datasheet).  

You have two choices- 10:1 with windings in parallel and 5:1 with windings in series. You probably want the higher ratio. 

I get 0.997 for the coupling coefficent: 

\$k = \sqrt{1 - \frac{L_{LEAK}}{L}}\$

The inductance of one low voltage winding (or two in parallel) is 10uH. The inductance of the high voltage winding is \$N^2\$ higher, or 1mH.