Drush config-set not working with php5

[klonos]

This is on php 5.6.40:

Command config-set requires Drupal core version 8+ to run.                             [error]
The drush command 'cset system.core preprocess_css 0' could not be executed.           [error]
Command config-set requires Drupal core version 8+ to run.                             [error]
The drush command 'cset system.core preprocess_js 0' could not be executed.            [error]
Command config-set requires Drupal core version 8+ to run.                             [error]
The drush command 'cset system.core error_level all' could not be executed.            [error]
Command config-set requires Drupal core version 8+ to run.                             [error]
The drush command 'cset admin_bar.settings position_fixed 1' could not be executed.    [error]

lando drush st
 Backdrop version         :  1.21.x-dev            
 Site URI                 :  http://test.lndo.site 
 Database driver          :  mysql                 
 Database hostname        :  database              
 Database port            :  3306                  
 Database username        :  backdrop              
 Database name            :  backdrop              
 Backdrop bootstrap       :  Successful            
 Backdrop user            :                        
 PHP configuration        :                        
 PHP OS                   :  Linux                 
 Drush script             :  /usr/local/bin/drush  
 Drush version            :  8.3.5                 
 Backdrop Drush           :  1.x-1.x               
 Drush temp directory     :  /tmp                  
 Drush configuration      :                        
 Drush alias files        :                        
 Install profile          :  standard              
 Backdrop Settings File   :  ./settings.php

The script I use throws no errors if php being used is 7.0+