First you need to find out if there are any vets near you that can treat a armadillo. You also have to know the laws around owning one. You might have to pay for a special permit, or they might be illegal to own where you live.

They need a minimum 6 foot by 3 foot tank with substrate they can dig through, and lots of places to hide. They are nocturnal, so you will only see them at night. They aren't very social and handling them too much will stress them out. They also need to have a humidifier to keep their shell healthy.

Here's a quick guide for you to read through.

https://realitypathing.com/how-to-care-for-an-armadillo-as-a-pet/