HI,
The DHL shipping plugin available on our marketplace is an all in one solution:
www.hikashop.com/marketplace/product/287-shipping-dhl.html
As explained on that page, it will provide tracking information from the purchase, yes.
However, for this to happen, the data of the order needs to be sent by the plugin to DHL, either by clicking on the button on the orders listing in the backend, or by activating the automatic feature.
And for this to be possible, a DHL shipping method (with its shipping fee automatically calculated by DHL) added by the shipping plugin needs to be selected by the customer during the checkout.
So if you have your own "manual shipping methods" which don't rely on the DHL plugin, the DHL plugin won't be able to send the data of the order to DHL nor retrieve the tracking information.
You would have to switch to this plugin and disable the manual shipping methods you had created in the past.