Json schema validation if/then ignored

Question

I am using the schema in here: https://jsonschema.dev/s/5iht5 in my mac. But the validator doesn't seem to understand if.

warning: the following keywords are unknown and will be ignored: [if, then]
  level: "warning"
  schema: {"loadingURI":"#","pointer":"/definitions/legal/allOf/0"}
  domain: "syntax"
  ignored: ["if","then"]

This does not work in MAC / AL2 OS.