It sounds like the website you’re automating is running on some kind of framework. While you technically can do everything with URLConnection it’s going to be challenging and I’d instead recommend you do it all in a DesktopHTMLViewer using Javascript.
You’d load your page, and then come up with a script to fill in the number in your ID field and click the find button, then run it with .ExecuteJavascript. Once the page has updated you prepare another javascript to extract the 10 fields you want and send them back to xojo using executeInXojo and capturing them with the JavascriptRequest event.
No API available - I only need a few of the many fields. Thank you Christian! I was floundering for a starting point. There are also a couple examples of XOJO with javascript that I can work from. Thank you for your detailed answer.
Not sure what OS you’re on, but this is the kind of thing that Microsoft Power Automate is pretty good at accomplishing with no coding required. You can then export the data into a csv or database to pass along to a companion Xojo app.