Condo ceiling leak from another unit

[Imed Rebhi]

TLDR: unit above ours is possibly causing leak into our attached garage through the ceiling. How do we pursue this fix?

Our tenant informed us that there is a 6ft long puddle in the attached garage that appears to be coming from the garage ceiling near a pull down access. When we purchased the property two months ago the inspector had noted water marks in this area but said the readings were all dry and to monitor for leaks coming from plumbing from another unit's second floor. Through our renovations and applicant showings a water problem was never noted. However our tenant mentioned there has been a lot of rain. Based on the floor plan, we know a different unit has a second floor above our garage and it is likely not a roof/rain issue. How do we go about this fix if someone else's unit plumbing turns out to be the cause of the leak? Are we responsible for the cost of the fix? There is an HOA but it is volunteer-run and largely impossible to contact (we actually don't have one as the POC stepped down). Not sure how or if the HOA could help anyway. Our home warranty does cover "pipe leaks"...but it wouldn't be our plumbing. Bottom like, we want to resolve the water issue ASAP. What steps should we take?