To add a custom text item to Portfolio Page - Grid, like this
You can use this code to Website > Website Tools > Code Injection > Footer
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.0/jquery.min.js"></script>
<script>
$(document).ready(function(){
$('<a class="grid-item grid-custom-text"><span>You know what? It is beets. I have crashed into a beet truck. Jaguar shark! So tell me - does it really exist?</span></a>').prependTo('div#gridThumbs');
});
</script>
<style>
a.grid-item.grid-custom-text {
position: relative;
}
a.grid-item.grid-custom-text span {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
width: 100%;
}
</style>