Link to new HTML page in same root folder not working - html

Question

Forgive the stupid question -- i know i'm doing something retarded, but I'm kinda stuck.
I'm a complete newbie -- and I inherited this website that is build on spring, thymeleaf, hibernate, java and a bunch of other technologies that i'm still learning. The original developer will not take my calls.
All the development is being done on Eclipse -- and I can get the existing project to run and build on my laptop.
I'm trying create a new page and link to it from my main default page (index.htlm).
I can create the href tag to an "existing" html file in the root folder.
But when I reference a new html page in the same directory -- the reference goes to 404.
What am I doing wrong.
Here is the original html snip:
<!-- Contractors -->
<div class="col-md-3 col-md-offset-1 col-sm-10 col-sm-offset-1 box-shadow 10px 10px " style="padding: 50px">
<span class="h1 type--bold">Contractors & Handymen</span><span class="h2">Looking for side hustle?</span>
<p class="lead">Be alerted to in-network jobs.</p>
<div class="row">
<div class="col-sm-12 col-xs-12">
<a th:href="#{/company}" href="company.html"
class="btn btn--sm btn--warning"><span
class="btn__text type--uppercase">Register Here</span></a>
</div>
</div>
</div>
I created a page in the same directory as "company.html" the file name is "signUpContractor.html"
And I updated the html snip as such:
<!-- Contractors -->
<div class="col-md-3 col-md-offset-1 col-sm-10 col-sm-offset-1 box-shadow 10px 10px " style="padding: 50px">
<span class="h1 type--bold">Contractors & Handymen</span><span class="h2">Looking for side hustle?</span>
<p class="lead">Be alerted to in-network jobs.</p>
<div class="row">
<div class="col-sm-12 col-xs-12">
<a th:href="#{/signUpContractor}" href="signUpContractor.html"
class="btn btn--sm btn--warning"><span
class="btn__text type--uppercase">Register Here</span></a>
</div>
</div>
</div>
output looks like this:
enter image description here
but when i click the link get this:
enter image description here
do i need to register the page with thymeleaf? or something?
if i reference other pages in the folder (that was existing prior to me taking over) such as "about.html" or "contactUs.html" the href works just fine. But any new page I create will go to 404.
Thanks for the kind soul that can help me navigate this.
Apologize in advance for the newbie question, i'm just out on the deep-end right now.
:-)