If using 0-10v analoge to control spindle. You set it as PWM on spindle control page.
On motor outputs page
Spindle Step = pin number of 0-10v output on board. (ie 17 if yours is that(.
Spindle Dir leave as 0.
Dir is controlled by M3-M4 on spindle relay control page.
You have M3 as output 1 yes?. Your board pin number should be assigned to output 1 in ports and pins.(not to spindle direction in motor outputs page).
M4 is output 2 yes?. Assign output 2 to a false pin.
So example if 0-10v is say pin 17 and dir relay is on pin 1 and board is classed as port 1:
Motors:
Spindle = Step = 17 / Dir 0.
Outputs:
Output #1 = pin 1 port 1
Output #2 = pin 1 port 0 (effectively inactive)
Spindle:
Relays = M3 = out #1, M4 = out #2.
Wiring relay connect FWD to NC, ,REV to NO terminals,
Now when M3 is called the relay for your direction on P17 should go NC (on), when M4 called relay will go NO (off).
Test using MIDI. If it works backwards tick or cross active high/low setting to reverse it.
When running spindle S the voltage should now vary on Pin 1.
If on the 0-10v output it is 10v at idle and 0v at full speed,, reverse this using Step active high/low tick/cross..
Something like this anyway.
Double check your pin numbers first..
Test 0-10v out with multimeter before connecting drive.