Example: The URL you want to render has a query string in it like
https://www.google.com/search?hl=de&source=hp&q=qualidator&meta=&aq=f&oq

If you want to pass this URL to html2PDF, you need to make sure that the URL encoding of the URL takes place before adding it to your rendering path.

The encoded URL looks like this:
https%3A%2F%2Fwww.google.com%2Fsearch%3Fhl%3Dde%26source%3Dhp%26q%3Dqualidator%26meta%3D%26aq%3Df%26oq

Use a URL encoding similar to http://www.albionresearch.com/misc/urlencode.php for that.

The finished encoded URL for rendering will look like this:
https://api.html2pdf.solutions/html2pdf/?UrlToRender=https%3A%2F%2Fwww.google.com%2Fsearch%3Fhl%3Dde%26source%3Dhp%26q%3Dqualidator%26meta%3D%26aq%3Df%26oq

If you want to add more parameters this is no problem. Here is an example:
https://api.html2pdf.solutions/html2pdf/?UrlToRender=https%3A%2F%2Fwww.google.com%2Fsearch%3Fhl%3Dde%26source%3Dhp%26q%3Dqualidator%26meta%3D%26aq%3Df%26oq&FileName=Example