First, you need to Sign In with your email and password inside Project Plan 365 application. You can get a link to your project only if it is saved on a cloud platform by clicking menu Team Share – Share or menu File – Share. Viewing and updating the project require authentication on the cloud platforms or SharePoint, respectively, and permissions need to be granted there, otherwise, the application will warn the team members that they do not have enough rights to view/update the MPP file.