How to handle subscription response in imapflow?

Question

does anyone can help me or give me some links in able to/how to handle subscription response using imapflow. I am already manage to subscribe using these code:

await client.connect();
                let lock = await client.getMailboxLock("INBOX");
                try {
                    await client.mailboxSubscribe("INBOX").then((res) => {
                        console.log(res); //true
                    }).catch((err) => {
                         console.log(err); 
                    });
                }
                finally {
                    lock.release();
                }

I am also receiving response: {"level":20,"time":1679592996412,"pid":id,"hostname":"host","component":"imap-connection","cid":"id","src":"s","msg":"* 208 EXISTS","cid":"id"}

Thanks in advance