curl --request POST \
  --url https://api.member.dev/api/v1/hubs/{hub_id}/spaces/{space_id}/join \
  --header 'Authorization: Bearer <token>'

{
  "data": {
    "attributes": {
      "contact_id": "<string>",
      "space_id": "<string>",
      "is_muted": true,
      "joined_at": "<string>",
      "last_read_at": "<string>"
    },
    "id": "<string>",
    "type": "<string>",
    "links": {
      "self": "<string>"
    },
    "meta": {},
    "relationships": {}
  },
  "included": [
    "<unknown>"
  ],
  "links": {
    "self": "<string>"
  },
  "meta": {}
}