I created a "testTeam" type with Max Ownership Per User set to 1 (mandatory).

So for a single user I should not be able to create 2 teams of this type where he is the owner.

But I can, see for this user :

{
  "@class": ".ListTeamsResponse",
  "teams": [
    {
      "owner": {
        "displayName": "Guest51766",
        "externalIds": {},
        "id": "58de78e20a162ad63ea89033",
        "online": true,
        "scriptData": {
          "lastVersion": 102,
          "country": "FR"
        }
      },
      "teamId": "58de78e20a162ad63ea89033-Following2",
      "teamName": "following",
      "teamType": "testTeam"
    },
    {
      "owner": {
        "displayName": "Guest51766",
        "externalIds": {},
        "id": "58de78e20a162ad63ea89033",
        "online": true,
        "scriptData": {
          "lastVersion": 102,
          "country": "FR"
        }
      },
      "teamId": "58de78e20a162ad63ea89033-Following",
      "teamName": "following",
      "teamType": "testTeam"
    }
  ]
}