The Shipping Agent Service page is a base Business Central page and does not affect Dynamic Ship. You can fill that in if you want to use that in helping to calculate planning times. Your Business Central partner would have more details on the use of that field.
DHL setup instructions can be found in our knowledgebase:
For TForce, Insight Works now has Banyan and 2Ship integrations available for freight (LTL/FTL) carriers in Business Central 16+ with Dynamic Ship 2.7+. First, billing will need to be arranged for the implementation via your Business Central partner. The LTL apps are free with the purchase of Dynamic Ship (no additional licensing), but the deployment, setup, support, training & testing is not included as part of the base Dynamic Ship fixed price project, so you can will need to have your Business Central partner email firstname.lastname@example.org to request a fixed price LTL project & SOW to be set up. First time installs are not available as T&M and will require a project. This is not a plug-in interface that can be installed as a demo or self-implemented because there are too many carrier specific requirements and settings, and the freight integrators do not give out demo accounts.