Steps
Open the organization menu, select Organization settings, then Users, and choose Invite new users.
Enter the adviser's first name, last name and email address.
Choose the role. Guest is the default and the recommended role for people outside your organization.
Give access only to the entities they work on. For a Guest, entity access stays empty, because Guests don't see entity data.
Select Invite. The adviser receives an email to set up their account.
Guest or another role?
Guests can only see notes and complete the tasks assigned to them. They can't access entities.
If an adviser needs more, for example to prepare corporate tax data for a few entities, choose another standard or custom role instead, and keep their entity access as narrow as possible.