Can a unit owner authorize an opening anywhere below their floor?
Do not assume so. Establish what part of the floor or plumbing is involved and who may approve work there. Finding a leak does not give anyone permission to change the building.
What to establish first
Describe the symptom without naming a pipe route: the room, the visible moisture or the consumption concern. Tell the person arranging the inspection that the property is in a shared building and name the management contact.
Ask whether management holds relevant plumbing or building drawings. Label drawings with their date if known; an old plan should not be presented as proof of the current installation. Make any previous inspection report available so testing does not begin from an incomplete verbal summary.

Agree the inspection scope
Before a visit, ask whether the proposed checks can be carried out within the unit or require a shared supply or service room. If the water needs to be shut off, ask management who must be told and who can approve it. Do not operate a common shutoff based on web instructions.
If opening the floor is recommended, ask for the evidence linking that area to the suspected leak. The estimate should identify who authorizes access, who makes the opening and who restores the building and floor finish.
Local checks and the next decision
North or South Hutchinson Island is not enough to select a permit authority. Supply the property address when asking the relevant building office about the actual repair proposal. The City of Fort Pierce Building Department handles permit and inspection questions within its jurisdiction; confirm applicability first.
City of Fort Pierce
Avoid a partial job described as complete
Agree separately on finding the leak, fixing the pipe, repairing the slab or structure and replacing the floor finish. Ask which professional is responsible for each included task. An inspector who identifies a likely location has not thereby approved a building alteration.
Before the area returns to use, establish which work remains and who will review it. Have the report name any areas or pipes that could not be checked, including those in another unit or on a shared supply.