autosuggestion.enable = true;

not
   autosuggestions.enable = true;

henrovnix_ok/README.org

@@ -2212,7 +2212,7 @@ Zsh gets installed and configured
         "kubectl"
       ];
     };
-    autosuggestions.enable = true;
+    autosuggestion.enable = true;
     syntaxHighlighting.enable = true;
   };
 }