An NZBGet post processing script that sets user, group and permissions of folders and files.

FixPermissions.sh

#!/bin/bash

################################################################################
### NZBGET POST-PROCESSING SCRIPT                                            ###

# Change user:group ownership and folder/file permission.

################################################################################
### OPTIONS                                                                  ###

# Set owner and group (yes, no).
setowner=no

# Put user here.
user=user

# Put group here.
group=group

# Set folder and file permissions (yes, no).
setmode=no

# Put file mode here.
mode=664

# Put folder mode here.
dirmode=775

### NZBGET POST-PROCESSING SCRIPT                                            ###
################################################################################


# Exit codes
#POSTPROCESS_PARCHECK=92
#POSTPROCESS_SUCCESS=93
POSTPROCESS_ERROR=94
#POSTPROCESS_NONE=95

POSTPROCESS=95

# Check if the script is called from nzbget 11.0 or later
if [[ "${NZBOP_SCRIPTDIR}" = "" ]]; then
  echo "*** NZBGet post-processing script ***"
  echo "This script is supposed to be called from nzbget (11.0 or later)."
  exit ${POSTPROCESS_ERROR}
fi

if [[ "${NZBPO_USER}" = "user" ]] || [[ "${NZBPO_GROUP}" = "group" ]]; then
  echo "*** NZBGet post-processing script ***"
  echo "[WARN] The user and group are set to defaults, check script settings."
  exit ${POSTPROCESS_ERROR}
fi

# Check if directory exists
if [[ -d "${NZBPP_DIRECTORY}" ]]; then
  # chown
  if [[ "${NZBPO_SETOWNER}" = "yes" ]]; then
    if chown "${NZBPO_USER}:${NZBPO_GROUP}" -R "${NZBPP_DIRECTORY}"; then
      echo "[INFO] Ownership set to ${NZBPO_USER}:${NZBPO_GROUP}"
      POSTPROCESS=93
    else
      echo "[WARN] User and group NOT set"
      exit ${POSTPROCESS_ERROR}
    fi
  fi

  # chmod
  if [[ "${NZBPO_SETMODE}" = "yes" ]]; then
    # recursively set perms on files
    if find "${NZBPP_DIRECTORY}" -type f -exec chmod "${NZBPO_MODE}" '{}' ';'; then
      echo "[INFO] File permissions set to ${NZBPO_MODE}"
      POSTPROCESS=93
    else
      echo "[WARN] File permissions NOT set"
      exit ${POSTPROCESS_ERROR}
    fi

    # recursively set perms on folders
    if find "${NZBPP_DIRECTORY}" -type d -exec chmod "${NZBPO_DIRMODE}" '{}' ';'; then
      echo "[INFO] Folder permissions set to ${NZBPO_DIRMODE}"
      POSTPROCESS=93
    else
      echo "[WARN] Folder permissions NOT set"
      exit ${POSTPROCESS_ERROR}
    fi
  fi
else
  echo "[WARN] Directory not found"
  echo "[DETAIL] $NZBPP_DIRECTORY"
  exit ${POSTPROCESS}
fi

exit ${POSTPROCESS}

Quick question. Script is called for and user/group are setup correctly.
However she fails with an "Operation not permitted" thus not setting requested chmod?

You can only change owner and permissions if the owner is trying to change it, so make sure your existing permissions and ownership are correct.