Basic Arlo login/account allows you to use one access email account and it can only be accessed via one device (computer \ phone \ tablets) at one point of time where a Grant Access option can help you create multiple users from different devices access the camera at the same time.
One can login into the Arlo account from any part of the world. On phone just by installing Arlo App. From App store or play store use the email account you provided for the first time of setup and the password. Or using and computer access the website https://arlo.netgear.com you can access the arlo account.
The account not only gives you access to live camera but the previous recordings , settings, subscriptions, payment mode etc.