How set session keycloak after connexion with custom login form - single-sign-on

Question

I am developing a prestashop sso module using keycloak, to check if a user is already logged in or not with the keycloak interface, I used the keycloak.js script:
const config = { url: urlKeycloak, realm: realm, clientId: clientId, "enable-cors": true, "cors-max-age": 100, "cors-allowed-methods": "POST, PUT, DELETE, GET"};
const keycloak = new Keycloak(config);
keycloak.init({onLoad: 'check-sso', checkLoginIframe: false}).success((authenticated) => {
console.log(authenticated);
}).catch(function(e) {
alert('failed to initialize');
console.log(e);
});
It works perfectly.
Now I want to login to keycloak through the prestashop login form (username and password) (I don't want to redirect to the login page of keycloak), so I used the keycloak REST API to get access_token ..., but my js script does not detect my login on keycloak, a priori It's missing brosser sessions of keycloak. Is there a keycloak REST api which saves sessions through the access_token?
Here is my connection code through the login form
$data['username'] = 'username';
$data['password'] = 'password';
$data['grant_type'] = "password";
$data['client_id'] = 'clientId';
$data['client_secret'] = 'client_secret';
$link = url_keycloak/realms/realm/protocol/openid-connect/token";
$curl = curl_init();
curl_setopt($curl, CURLOPT_POST, 1);
curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
curl_setopt($curl, CURLOPT_URL, $url);
$headers = array(
'Content-Type: application/x-www-form-urlencoded',
);
curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
// EXECUTE:
$result = curl_exec($curl);
curl_close($curl);