I'n not really sure exactly what it is you are looking to do.
Perhaps you could provide a link to your website and explain further what you are looking to do (and what you would like to happen).

In the meantime, from your topic subject ("How to configure Image click to open url in a part of the page?"), it sounds like you might want the content of the linkURL to appear on your gallery's web page, alongside your gallery. If so, then you could maybe create an <iframe> on your gallery's web page, with a specific id and name, and then use this id/name as the linkTarget to load the linkURL into the <iframe>.

For example:

    <!--START JUICEBOX EMBED-->
    <script src="jbcore/juicebox.js"></script>
    <script>
    new juicebox({
        containerId: 'juicebox-container',
        imageClickMode: 'OPEN_URL',
        galleryWidth: '600',
        galleryHeight: '400'
    });
    </script>
    <div id="juicebox-container"></div>
    <iframe id="xyz" name="xyz" width="600" height="400"></iframe>
    <!--END JUICEBOX EMBED-->

A sample <image entry in your gallery's 'config.xml' file might look something like this:

  <image imageURL="images/image_0001.jpg"
    thumbURL="thumbs/image_0001.jpg"
    linkURL="http://www.example.com"
    linkTarget="xyz">
    <title><![CDATA[Image title goes here.]]></title>
    <caption><![CDATA[Image caption goes here.]]></caption>
  </image>

I hope this helps.
If not, then please try to explain in greater detail what you are looking to do and I'll try to help further.
Thank you.

Thank you for the clarification.
So you want to run a custom JavaScript function when a main image is clicked...
Juicebox-Pro was not designed with this in mind but you could try the following:

(1) Set imageClickMode="OPEN_URL".
(2) Set all your linkURL entries (in the gallery's XML file) to linkURL="javascript: custom_function();" (to run a custom JavaScript function named custom_function() in the gallery's embedding page when the image is clicked).
(3) Set all your linkTarget entries (also in the gallery's XML file) to linkTarget="_self".

In  order for your function to know which image has been clicked (and, therefore, how to proceed), you could either:

(1) Pass a parameter (or parameters) to the custom function, e.g.:

linkURL="javascript: custom_function('abcdef');"
linkTarget="_self"

<!--START JUICEBOX EMBED-->
<script>
    function custom_function(text) {
        alert(text);
    }
</script>
<script src="jbcore/juicebox.js"></script>
<script>
    new juicebox({
        containerId: "juicebox-container",
        imageClickMode: "OPEN_URL"
    });
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->

... or:

(2) Use the Juicebox-Pro API (in this example, the getImageIndex() function) within the custom JavaScript function to determine which image has been clicked.

linkURL="javascript: custom_function();"
linkTarget="_self"

<!--START JUICEBOX EMBED-->
<script>
    function custom_function() {
        var index = jb.getImageIndex();
        alert('Image #' + index + ' has been clicked.');
    }
</script>
<script src="jbcore/juicebox.js"></script>
<script>
    var jb = new juicebox({
        containerId: "juicebox-container",
        imageClickMode: "OPEN_URL"
    });
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->

Please note that this will not work if you use a baseUrl or when the gallery has been expanded.

I hope that this points you in the right direction. (Just replace the contents of the custom JavaScript function with your own code.)

Using my example, you'd still need to use the custom_function() JavaScript function but setting imageClickMode="OPEN_URL" would essentially take the place of your jQuery click handler (at least for clicks on the gallery images... you'd still need your own custom click handler for your regular non-gallery links).
Instead of:

<script>
    function custom_function(text) {
        alert(text);
    }
</script>

... use:

<script>
    function custom_function(parameter) {
        callDinamicPage('mainContent', parameter, 'page', '');
    }
</script>

You'd also need to pass the value of what would be the data-toggle attribute (in a regular non-gallery link) as a parameter in the call to the function (in the linkURL), e.g.:

linkURL="javascript: custom_function('xyz');"

(This assumes that 'xyz' is a valid data-toggle attribute for your scenario. Just change this for each linkURL as necessary.)

As I mentioned above, you'd still need to include your own custom click handler:

<script>
    $('.link').click(function() {
        callDinamicPage('mainContent', $(this).attr('data-toggle'), 'page', '');
    });
</script>

... on your web page to handle your regular non-gallery links.

I got everything except this part... sorryyy!!!

In the non-gallery pages, data-toggle calls a page to load. For example I have a page called congreso2019.php so my script is data-toggle="congreso2019"

In the link option you describe I tried linkURL="javascript: custom_function('congreso2019');" Is this correct? Because it didn't work...

I'm sure I followed the rest of your instructions correctly.

Thanks again for all your help :)