You need to make the timer PT a tag, then that tag can be linked to the HMI. Note that although the PLC will allow you to enter times like 5min27s, all times on the HMI will be in ms.
If you want to adjust this, you can do scaling in the properties of the HMI tag.
ALSO, note that the PLC won't ever update the timer (and therefore it will never finish) if you only monitor it from the HMI. Timers update when you read the Q tag (output) or the ET tag (elapsed time). Its a little bit of system magic that isn't really obvious.