there are not so many rules is very easy.
you must have working visa.
a letter sign buy your company to show how much is your salary.
if you are singel a singel proof paper tracelate by offcial notary.
if you are married same but than you need to have marrige paper and also trancelate it by official notry.

if you got all those paper you can even get a morrage on your house.

But later when you get the house, you have to text for foreigners is a bit more expancief in shanghai. other city i don't know, Good luck is a good idee buy house in china best invesment you can do

The rules are constantly changing. Ask a realtor.

Some neighborhoods are even closed to foreign purchasers.