Mqtts tests on broker: connection not allowed

Hi, I would like to use postman for some tests on hivemq(serverless cluster), somebody know how?
I made a lot of attempts with no results…

Currrent Postman version: 10.24.11

The broker (server) data are something like these:

Cluster Url:

f2s34adasdwq1wq1e534ac98c146abdb.s1.eu.hivemq.cloud

Port:

8883

Websocket Port

8884

TLS URI

f2s34adasdwq1wq1e534ac98c146abdb.s1.eu.hivemq.cloud:8883/mqtt

Websocket URI

f2s34adasdwq1wq1e534ac98c146abdb.s1.eu.hivemq.cloud:8884/mqtt

It is necessary to install on client side the certificate. On the forum I found this:

HiveMQ Cloud cluster doesn’t need client.pem and user_key.pem. HiveMQ Cloud cluster authenticates the client by username and password (so called “simple auth”). In order to “trust” the server, you device might need a root CA cert. You can download the root certificate here . This will create a file called isrgrootx1.pem, which you can use as “Server Certificate” (cacert.pem)

The certificate is downloadable here:
https://letsencrypt.org/certs/isrgrootx1.pem

I’m here just to know if is possible by MQTT or WebSocket.
I installed the certificate on the setup


I never reached the connection.

Please help me…