Question about posting code in pages

Hi, I’m a WordPress newbie with website issues! I had a designer make and set up my website, https://www.jessicafrost.com, and I do the maintenance (which is relatively easy for me to do). But I’ve recently joined a website, https://www.musicteachershelper.com, for my business and it allows me to post a log-in button for my students on my WordPress website. I’ve tried to switch to the html side but when I insert the code it deletes everything else on the page (but the button does show up in the preview). Is there a way to post t he button on the page AND keep everything that’s already there? The page I’d like to add it to is https://www.jessicafrost.com/lessons/current-students/. Thanks in advance for any assistance you might able to provide!

The code that is supposed to be inserted is below:

<script type=”text/javascript”>
var studioTitle = “My Music Studio”;
</script>
<script type=”text/javascript” src=”https://www.musicteachershelper.com/js/remotelogin.js”></script&gt;