With the Udacity shared plan from JoinBareng, you get login access to a shared account for the Udacity Monthly Subscription program. The account is used together with other slot members as planned, and the admin will send the credential after your payment is confirmed and the group is ready to be activated.
There are important rules to keep shared access smooth: do not change the password or email of the account, and do not log out other devices. Because the account is shared, any action that affects access will affect all members. As long as the rules are followed, your learning access stays comfortable.
The plan currently available is the 1-user (private) plan, so you get full access without sharing with anyone. The group plan with up to 2 people per group will be opening soon—worth waiting for if you want to take a Udacity Nanodegree at a more affordable cost per person.