I think i finely got it....i hope.
1. Open the .step file
2. Machining -> Add New 3D Operation -> Attach Operation...
3. Change the "minimum z" to the working depth of the solid (for me it was -20)
4. I used the "Rectangle drawing" tool to make the sketches where i wanted to do the Pocket Operations
5. I used the sketches to make the rough Pocket Operations with a bigger tool
Then i tried to make the final Pocket Operation with the same sketches but that didn't work, so i made a second file where i only do the final pocket. For the final-pass tool-path to work, the "step down" value must be the same value as the "final depth". If the "final depth" is negative, "step down" must be the same positive value.
I had "final depth= -10.5" and "step down=10.5"
And i also used "zig zag"
"keep tool down" doesn't seem to work.
I hope this helps someone...and if i'm wrong here, please do correct me.