Neighbour made a noise complaint to the police

Just moved to Fredericton this evening. Made some unintentional sound while unpacking around 7-8 pm. The people downstairs made a complaint and the police came to check the situation around 1 am. I am absolutely sure none of the sound we made was worth complaining. What can I do? The landlord warned me about this sorta behaviour from this tenant. Please help!

Update: Just talked to the lady living downstairs. Surprisingly, turned out to be extremely friendly and welcoming. She's a reiki so she needs to sleep early and in a quiet setup. Just explained to her that it's the sound of our unpacking not from our shoes or anything. She was happy to share contacts and let us know immediately of any further inconveniences. Thanks for all the comments and suggestions!