Let's Encrypt error

[Comograma]

I'm trying to run/test the demo app IndyHttpsDemo but I can't get it to work.
If I use link http://127.0.0.1:8888/, I will get this error:
Error details:
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Exception message : Secure mode is required for this form.
Depending on the error condition, it might be possible to restart the application.
Exception class : EIWException

If I use link https://127.0.0.1:8888/ it will spin forever and won't load.
What am I missing?