The currently available Masterchannel shared plan is the 1-user Artist tier on a monthly basis. The Masterchannel account is used jointly under strict rules: you log in with the credential provided by the admin, you must not change the account password or email, and you must not log out other devices. These rules exist so every slot keeps reliable access to the mastering service.
Because this is a 1-user package, you receive full access to your own account handled by JoinBareng, not a shared account with other people. Group packages allowing up to 3 people per group on the Artist tier are scheduled to open later, so for now availability is 1 user per package until the next announcement. The package price is displayed automatically on the package card on the product page.
If you choose to hold for a group package that allows lower per-slot cost, the typical flow is: you pay your slot via QRIS, then wait for the group to fill to its quota. Once the group is full, the admin activates the shared account and sends access to all members. While waiting, no access is granted yet and you cannot master until the account is activated.