How to link a speaker with an attendee profile?

Unfortunately, there's no way to link a speaker to an attendee profile and vice versa.

If you'd like your speakers to join your event with the app, you need to invite them as attendees (or other company members depending on the access level you want them to have). And the other way around, if they already have an attendee profile and you need to add them as speakers, you need to create new speaker profiles for them.