how to use encode base64 with jira cloud api via postmann

[Bruno Bernadet]

i seek on the community group and i find that some errors could occur because of the authentification. i try to fix it on postmann but i dont find the correct way. i use api token and i see that a lot of users use mail: api encoded on base64 on the header . i a  a noob with postman so i dont see how in the api how to settle this 

so -what i have to choose in authorization : Api key or bearer token?

- have i to modify the body of the pre request script ?

pm.sendRequest({

    //url: pm.environment.get("api-url") + 'v2/authenticate',

url:  'https://xray.cloud.getxray.app/api/v2/authenticate',

    method: 'POST',

    header: {

        'content-type': 'application/json',

        client_id: pm.environment.get("client_id"),

        client_secret: pm.environment.get("client_secret") 

    },

    body: {

        mode: 'raw',

        raw: JSON.stringify({ client_id: pm.environment.get("client_id"), client_secret: pm.environment.get("client_secret") })

    }

}, function (err, res) {

    pm.environment.set("AUTH_TOKEN", res.json());

});

I have a 200 response while using authentificate but for a get project id i have 

   "error": "Failed to parse Connect Session Auth Token"