If you follow exactly the tutorial How to create new user for my ERP5 Instance, you will be able to login with the created user. A user can only access your ERP5 instance, if he has the required permissions. The permissions in ERP5 are defined by Assignment. Depending of the categories defined in the Assignment (group, site function) a user may have different access rights. In the ERP5 standard configuration used for OSOE classes, a simple security configuration is implemented using the group category only: Every person which has a started assignment where group is your company can access ERP5. Therefore the following requirements have to be met, so that a person can login.