You will need your ORCID login details.
If you don't have an ORCID profile you can create one on the ORCID website using this tool.
The 'Start' button redirects you to the ORCID website to sign in and give permission for Europe PMC to access your ORCID record (this allows you to use other Europe PMC features which require sign in, such as saved searches).
You will be returned to the Europe PMC website to select your articles and send them to your ORCID profile.