I finished setting up the webservice routes according to Apple documentation and I am able to sign and provide passes. Unfortunately I am experiencing the following problem. When I define the webServiceUrl as "https://localhost:5000/wallet/" the signing of the pass works as expected. I am then using the pass in the iOS Simulator where I have enabled the "Allow Http Services" in the developer settings but I am still getting the "An SSL error has occurred and a secure connection to the server cannot be made" error. Trying then to use http instead of https directly in the definition of the webServiceUrl in the pass.json file produces a signing error. Do you know which steps have to be made to be able to test pass updates locally?
The warning is telling you everything you need to know.
Change your webServiceUrl to http://localhost:5000/wallet/. The developer option means that you don't have to use https and the pass should still install on any device with "Allow Http Services" set.