First extract the file which you 

have doenloaded.Then you will have two  filles named dffand txd

then you have to download two application which is 1.gta img tool

2.txd tool to download txd tool click in this link https://www.modapkdown.com/txd-tool-mod/ and download the apk.

then open gta img tool and go to you android data folder and find com.rockstar.gta.sa and go to textdb folder and click on gta.3 img.Then click on that three dots which is given on the upper right side.After clicking it click on add files to replace when you will click on a new pop-up will come select that file which you have extract and select that dff files.when you will select that file just click again on that dots and click on rebuild it will take few second to rebuild when its finished rebuilding then open your txd tool and give permission and go to android data and select gta sa folder and textdb and then go to txd folder and select that file to tx int folder and click on add texture when you will click that add texture a pop-up will come select that txd file and import.and then start the application and enjoy tha mod.