So i tried once again with a firefox "private" window - but this failed again.
Next idea was to use a completely new installed browser: so i tried with a fresh google-chrome.
But the error still remained:
Let's hope Oracle support has another thing which will put me onto Oracle cloud.
There is a tiny link "click here" just abouve the blue button. This link a have to use with the verification code provided by Oracle support.
But then the error is:
I checked this a VISA and MASTERCARD. Neither of them worked...