Marlin Firmware Auto Leveling only re-centers the XY-axis (Delta printer)
You are correct to define the constants AUTO_BED_LEVELING_LINEAR and Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN, be sure to define the following also:

#define Z_MAX_POS MANUAL_Z_HOME_POS


and

#define MANUAL_Z_HOME_POS 300 // Distance between the nozzle to printbed after homing



Note that 300 should be the distance from nozzle to bed after homing.


Please look into the configuration files of this Kossel Linear Plus and compare them with your own configuration files, you may have missed something.