AlgoDocs is designed to have an account with multiple users in it. Therefore, after you sign up at AlgoDocs and your account is created you can manage your users by clicking the username on the top right corner and navigating to 'Users'. There, you can add, edit or delete a user.
When you add a new user the password is sent to the email address you entered for the newly added user. Therefore, make sure you add a valid email address. Users can change their login passwords later. Moreover, you can disable any user from the list of users and enable back at anytime.
There is no limitation on the number of users you have in your account. However, the quota in your account is assigned to the account, not each user. Therefore, whenever any user imports a document the quota will be deducted by the number of processed pages for that document.