Users with a Partner role will only be able to access the calendar and bookings list. They can consult availability and create new bookings, however, they cannot delete or cancel any bookings nor see sensitive data. External bookings will be masked for users with a Partner role.
To create a login for a partner, access the Users module and add a new user. Make sure to select the role Partner before completing the details and saving.
Finally, edit the user and, from the Partner tab, assign the user to one of your existing partners. If you work with locations, make sure to enable which calendars the user will have access to from the Locations tab.
Please note that if the user. is not assigned to any partner and remains as "None / My own organisation" the data from all bookings will be visible to the user.
If you have not created any partners yet, make sure to do this from Sales > Partners. The following article provides more details on how to add a new partner: How to add a partner and create a referral booking.