Below is the command to add user to an IAM group where username is the name of the user and TeamA is the name of the group.
aws iam add-user-to-group --group-name TeamA --user-name username
Below is the command to add user to an IAM group where username is the name of the user and TeamA is the name of the group.
aws iam add-user-to-group --group-name TeamA --user-name username