It is a common saying that there is no such thing as bad publiity. But probably some people don't agree.
It might be desirable to contact the owners of Paronella Park and ask if they have any objections to that plot element. It is possible that they might not want to deal with possibly many requests to stay inside the castle, for example. And they might object to murders or other bad events happening in the castle or anywhere in Paronella Park.
It might be a good idea to mention in the story that people are no longer allowed to stay inside the castle, because of the events in the story - if your story has any events that might make the owners make that decision. If everything goes smoothly while your characters stay in the castle such an option won't be possible.
If everything goes smoothly when your characters stay in the castle, and their stay couldn't be considered a reason to discontinue letting people stay there, you might want to have the character who books the stay in the castle be told they are in luck, because they got the last open slot to stay in the castle. The owners are discontinuing that service to reduce their staff and payroll. And one or two staff members who wait on the visitors may mention that they will be out of work soon and ask if the vistors know anyone who is hiring.
Or possibly the character who books the stay will be told that this is an experimental program, lasting a few weeks or months, to have visitors stay in the castle, and if it goes well enough the owners might decide to continue having vistors in the castle. So the readers will know that it is not certain that people will be able to stay in the castle after the time of the story.
And you might possibly want to find out if there are any similar attractions nearby, and then be vague enough in your descriptions of the place and in the directions to the place that readers will be unsure which attraction is the location.
If the visit and stay in the castle is mentioned later in the story, the characters might forget some details and can't remember whether it was in Paronalla Park or in any similar attraction that your research might find in the region that could be confused with Paronella Park.