href from non-react environment into react environment

I am building a portfolio site for web applications (most of which I did not build) and I have an html file, which for sake I'm going to refer to as portfolio.html, that has no script of any kind, just html, css, and hrefs to web applications (which are hosted on the same site) and I want to be able to create a href in portfolio.html that will lead the user to a React web application. How do I do that? I didn't built the React application. I don't know which file to href to.

I've looked into deploying React apps, but the issue is the portfolio site isn't built in React and I don't want to rebuild it using React. I will also be hosting other web applications on this portfolio site that don't use react.