‘American Dream’ is worth 10 Gamerscore Achievement/Trophy which requires you to own an apartment, garage and an insured vehicle in GTA Online. You have several options when it comes to apartments and garages in the game but you will need a lot of money if you are going anything fancy.
After beginning the game and spending in some time in the ‘Online Mode’; Simeon will call you and ask you to bring in a vehicle for insurance and customization.
You can take any vehicle of your choice and take it custom shop to modify and insure it by absolutely paying nothing! You just need to bring in the vehicle and Simeon will take care of the cash payment. That’s all for insurance.
As for the apartment and garage; you need to be above Rank 5 before you could purchase your own properties. Now; there are multiple ways using which you can buy a property but we would advise you to use internet Real Estate to buy them.
Just take out your phone and check ‘Dynasty 8’ from the homepage and look for an apartment which has a garage with it. Successfully buying any property from the internet will unlock the Trophy/Achievement.
Note: Many people have confirmed that buying property from the property sign outside the buildings will NOT unlock the Achievement/Trophy; so we would advise you to stick to internet.