You set your own alarm code regardless of who previously owned the home. The system walks you through the process of setting your private codes. You are not connected to a provider until you call a service provider and ask to be set up and connected with them. You can do this with the provider of your choice. If you need a manual check online for one with the information you have. A service provider might also have recommendations for getting a manual but can usually walk you through any unit you have purchased when you contract with them. Most alarm systems have single button options to police, fire or ambulance once you have a contract and most importantly a forced entry code. You are already wired and your system is functioning but it won’t relate to anything until you start using an in and out code and get a contract with a provider for alarm service. Check with several for quotes.

My only suggestion would be to check and see if you can find a company name on the security box and search the internet for a contact number, tell them about your problem, and if you can prove that you own the condo currently they should be able to help you with disarming or replacing codes.
If you cannot find the company name, you’re only other option is to contact the seller of the condo for information or a handbook on how to use, set up or dis engage the product.
They should have supplied you with this information upon purchasing the condo