Your Taplink account can be accessed by people:
1. Who have your Instagram password.
2. Who receive notifications about new submissions where there is a direct link to sign in to your Taplink profile.
3. Who have shared access to your Taplink account.
4. Who have access to the email account to which Taplink is registered.
My Profiles - these are the profiles of your account.
Shared access - the profiles that you have been given access to.
To access the profiles from "My Profiles" you will need to sign in with the desired account. When you sign in with "Shared access" you sign in with your own account (the one you've been given access to) and then switch to the account you want (the one you've been given access to).
To set up other people's accounts, it's preferable to use "Shared Access".