Just for kicks, giggles & grins, try hitting WIN+R and in the text field for a program name, paste the URL and click "OK". That will invoke some form of the ShellExecute() WIN32 API function. If the shell environment has a URL handler registered, it'll launch an appropriate program. If that is successful, then WinBatch can invoke the same API function. In man cases, what I'd expect to have happen is for the default web browser to be opened with that URL, and if the protocol in the URL is well known, the browser may already have the capability of handling it like for HTTP, HTTPS, FTP, etc. If it's a less well known protocol not supported by default, there may be the possibility of having a browser extension of some kind installed to allow the browser to handle it.
Worst case, you have to research the protocol itself based on the RFC standards/specification document that defines it and then write code of your own to implement the protocol. I've written a Telnet client in WinBatch before using nothing but the TCP socket communications capabilities, so depending on the nature of the protocol, you might possibly have some success doing that kind of thing yourself.
For example, a Google search for the keywords 'url with "fmp" protocol' leads to the following results:
https://fmhelp.filemaker.com/help/14/fmp/en/html/sharing_data.17.6.htmlhttps://www.twdesigns.com/fmp_url_protocol/Those look like a very good place to start your research.