You are specifying a local path for the image. Even if the browser allowed you to load local files into your page
(they don't), it would be trying to load that image from the
user's file system.
It's highly unlikely that the user will have a file with the same path and filename as the file on your server. And even if they did, it's not going to be the same file.
But that's irrelevant anyway, because browsers
do not allow websites to reference files from the user's local file system. This is for security reasons, to prevent a malicious site from reading the contents of your computer without your knowledge.
Instead, you need to load the image using an HTTP or HTTPS path. This can either be a full URL, an absolute path on the current site, or a path relative to the current page. For example:
<!--
<img src="http://www.yoursite.com/images/download.png" alt="" />
<!--
<img src="/images/download.png" alt="" />
<!--
<img src="../images/download.png" alt="" />