Every service has a location and it decides what the booker sees before the meeting and what lands in the calendar invite.
Choose a location
Set it per service, under Services → your service → Advanced → Booking Location. Three options:
For in-person meetings you can also decide whether the address is shown publicly on your booking page or only revealed to people who’ve actually booked.
Beauty professionals, therapists and anyone with a studio want In-Person
with the address hidden until booking. It keeps a working address off the
public web while still putting it in the confirmed invite.
Video providers
For video meetings, pick which service generates the link under Settings → Profile → Conferencing:
Every booking gets its own link. Nothing is a shared, permanent room.
If your chosen provider can’t produce a link (say you picked Google Meet but
your Google connection has expired), Tikk falls back to Jitsi rather than
sending out an invite with no way to join.
Where the link comes from
The link is generated when a booking is confirmed, not when it’s requested. So a pending request has no meeting link yet and one appears the moment you accept.
On a paid booking that hasn’t been paid, the link in the booker’s email is the
payment link, not the meeting link. The meeting link follows once the
payment clears.
Changing a location later
Editing a service’s location changes it for future bookings. Bookings that are already confirmed keep the location they were made with, so nobody turns up somewhere you’ve since stopped using.
Rescheduling a booking re-resolves its location from the service as it stands now. See Manage bookings. 
