Login with postman with xray cloud API

Question

I have problems with Postman and xray cloud API I seek on THE WEB and I have some errors because of the authentification. I try to fix it on postman but I don't 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 don't see how in the API how to settle this.

If someone has a way or a tutorial with clear path

• I have this on my prerequest script. I use for client id and client secret an API token create for JIRA xray.
• My user is admin
• I've got with a post request with authenticate a status 200 OK with an authorization token but for the others request I have all ways the error beside

For example GET {{JIRA_BASEURL}}/rest/api/2/project/{{PROJECT_KEY}} (when I put directly this request on a navigatot I have a response) but with postman

    "errorMessages": [
        "No project could be found with key 'SCRUM'."
    ],
    "errors": {}
}

My prerequest 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());
});