How do you get into that link?
If we need to creat a cloud kasa cloud account, we can directly do it with kasa app.

You may refer to this link:
https://www.tp-link.com/us/faq-948.html

I got the link by debugging the app through a proxy because YOU CANNOT REGISTER FOR AN ACCOUNT USING THE APP because it just gives an error about the network being unavailable !!

I debugged the network traffic of the app and found the underlying issue. The invalid SSL Certificate.

Currently it is IMPOSSIBLE to create an account with the app. Try it!

Have you downloaded the kasa app on your iphone?
What's the error message did you get when you register account?

You can also try to register with another phone. If still same issue, attach a screenshot of the error.
Good luck.

This is not a Phone issue.

Don’t believe me? You try… try and create a new account on a UP TO DATE iPhone. See, you can’t.

The fact is that the SSL certificates used by TP-Link are now not trusted by Apple devices (and 99% of browsers)

You may misunderstand Kevin's answer.
If you can provide an error screenshot, it will be easier to help you analyze the problem.
What's the OS version on the iphone?
I just tried open the original link you provided, ca't open it after I choose to continue anyway.
It's better to try with another smart phone~

None of you seem to be technical enough to understand the root problem here.

I have an iPhone X with iOS 11. A standard configuration for 2018.

It seems no one from the official app team reads these threads or is even interested in fixing this.

The root problem is that THE WORLD has now stopped trusting Symantec SSL Certificates and so any secure iPhone now REFUSES to connect to a SSL site that uses a Symantec SSL Certificate.

https://www.bleepingcomputer.com/news/security/google-outlines-ssl-apocalypse-for-symantec-certificates/

https://www.theregister.co.uk/2018/02/07/beware_the_coming_chrome_certificate_apocalypse/

https://blog.mozilla.org/security/2018/03/12/distrust-symantec-tls-certificates/

Therefore until someone replaces the SSL Certificate on wap.tplinkcloud.com NO ONE USING ANY CREDIBLE DEVICE HANDSET like an up to date iPhone will be able to register.

That is the problem.

I cannot show you an error message on the phone, because the only message was something like "cannot connect to the server at the moment, try again later" - this is why I debugged the issue.

My problem now on the iPhone X with development iOS 12 on it is different, now I cannot get that far as it hangs forever when I press the chose location button in the registration form.

Hey, I got the similar error message before. I successfully logged in after updating the new app.
You may try to update the Kasa App to v2.2.0 , released recently.
Good luck~

PhilETaylor wrote

My problem now on the iPhone X with development iOS 12 on it is different, now I cannot get that far as it hangs forever when I press the chose location button in the registration form.

When I talked with them today they seemed shocked by this behavior...and yet it's here on the forums from more than a week ago and the original problem from a month ago. Maybe another brand would be better...customer service is already questionable.

I am having the same problem.

TP-Link smart device does not support hidden Wi-Fi.

Do you mean you can't get it connect to a hidden Wi-Fi?