"Ameli" is the name of the French Social Security website.
To create your Ameli account, you first have to be registered with the Assurance Maladie (Health Insurance or French Social Security) and obtain a permanent Social Security number.
See our related articles
French Social Security scheme for health coverage, general information / Sécurité Sociale (CPAM - Caisse Primaire d'Assurance Maladie)
Registration process to the French social security for foreign students / Sécurité Sociale et étudiants étrangers
Comment reconnaître mon numéro de Sécurité Sociale? / How to recognize my own Social Security number?
If your Social Security number starts by 7 (for a man) or 8 (for a woman), it means that it is a temporary Social Security number.
You can create your Ameli account only with your permanent Social Security number, using the first 13 digits.