I hope all in good health in this not easy time.
I was faced with the following situation. The guys on my team made a SOAP API penetration testing for one of our clients. Now is the time for re-testing, and the colleague who conducted the initial testing is now on vacation. After talking to him he told me that you need the customer to ask for the XML (WSDL etc) files for the full testing of that API since otherwise not be able to generate requests to the API or response will not be correct.
The first hearing that need the original XML files to the API for testing. Perhaps if the use of such tools as SOAP UI , it is not enough only the API URL (example: https://api.my.com/test/proxyservice/getdata?wsdl)