Stray animals on the streets are ownerless and unattended; adopting them doesn't require any paperwork. However, some cities have stricter regulations for cats and dogs, requiring licenses for each pet. You can consult the relevant authorities to see if you need to apply for a license. Afterward, you can take the stray animal to a veterinary clinic for a checkup to see if it has ear mites or parasites, and have the veterinarian treat it. 
Stray pets are very pitiful, and it's normal for them to evoke compassion in some people, leading them to want to adopt them. This is because everyone has a kind heart and wants to do their best to help stray animals. These animals are unattended and spend their days sorting through garbage and catching mice or birds to eat. If you want to adopt one, you can feed the stray dog or cat you like to get it used to you. Once it shows you its belly button, indicating trust, you can prepare a cardboard box, put the stray dog or cat inside, and take it to a veterinary clinic for a full check-up before taking it home. Initially, you can keep it on the balcony because it shouldn't be bathed immediately after deworming; wait three or four days before bathing it.
If you need to obtain a dog license or other certificates, you can do so; it's not particularly troublesome or expensive. Afterward, you should ensure the stray animals are vaccinated to maintain their health. Then, let the stray animals get used to your home by taking them out for walks more often, especially dogs. If it's a cat, you can prepare a cardboard box for it to stay in for a while to familiarize it with the house before letting it out. A large house can be very frightening for cats, and a cardboard box can provide a safe haven.
Stray animals are generally quite independent and wary of humans, so you must be careful when adopting them to avoid being bitten.
