Hi,
These notices are not linked to the problem.
You see them because you try to access the URL directly which is not the case with ShipStation which adds additional parameters to it. We'll remove the notices next week, but it won't help you.
As Jerome and Philippe told you before, the problem is not with the ShipStation plugin or HikaShop or the way you configured it.
The problem is the fact that your website is not accessible to anyone.
When I try to look at that URL, I don't get these notices, I get the same error philippe gave you before which is that the website is not accessible.
And if your website is not accessible, ShipStation cannot contact it in order to get the orders.
What you need to do is to fix the fact that your website is not accessible. Regardless how much you pay us, how many times you ask us, or if you use another cart solution, you will still have the exact same problem with ShipStation until you make your website accessible. If you don't know why your website is not accessible, I would recommend you to contact your hosting company so that they can check it.