Good morning Bjorn! We're (really) sorry you're having trouble getting onto code.europa.eu
Now, let's see
From what we can tell, it seems you're not yet finished with the EUlogin part?
Does this website provide any help?
https://trusted-digital-identity.europa.eu/eu-login-help/external-self-registered-account-faq_en
Else, there is also an email address
https://trusted-digital-identity.europa.eu/still-need-help-eu-login_en
Also, please note that you don't need an account on code.europa.eu to study and reuse the code.
Accounts are required only if you intend to contribute to a project.
We explain that here https://code.europa.eu/info/about in the section on public access.