Will this jack work on a concrete floor or only asphalt?

Works on both. Use a solid, level surface and place a wooden block under the base to distribute weight if the floor is soft or uneven. Never jack on dirt or gravel.

Do I need to use jack stands with this?

Always use jack stands rated for your vehicle weight. A jack is a lifting tool, not a support tool — stands are non-negotiable for safety whenever you work under the vehicle.

What maintenance does the jack need?

Keep the hydraulic pump clean and store in a dry space. Check the rubber handle and base pad periodically for wear. Refer to the owner's manual for fluid specifications if servicing becomes necessary.