Customizing the Nav walker

I am forced to use a navigation markup like this:

<nav role="navigation" class=" navigation-menu">
<a href="index.html" class="navigation-link">Home</a>
<a href="contact.html" class="navigation-link">Contact</a>

The current output with Soul is:

   <nav role="navigation" class="navigation-menu">
        <ul id="menu-primary_navigation" class="w-nav-menu navigation-menu">
          <li class="active menu-item menu-home"><a href="//localhost:3000/roots/">Home</a></li>
          <li class="menu-item menu-sample-page"><a href="//localhost:3000/roots/sample-page/">Sample Page</a</li>

Do I need a custom nav walker?

Yes, this is not a Sage or Soil specific thing.