Then when you start the game the mod files you installed will be there and will work well. After that right-click anywhere and choose paste. Go to Documents > Electronic Arts > The Sims 4 > Mods. You can navigate these folders to the Sims 4 mods. Also, this is the file type suitable for Sims 4 mods. Open the folder and check the contents in it. This file will now extract to the folder. If you are using the Winrar extraction tool then click Enable Custom Content and Mods. Now you have to open the download folder.
Then save all the downloaded files in the folder. Then click the download button on the website and download it all. There are many available on the internet. If you want to download the mods for your Sims 4 then you have to find the content you want. Then in the game options tick the Enable Custom Content and Mods. So to turn it on go to the menu button in the game. So before adding the mods you have to turn the mods in the Sims 4. There is an option in the Sims 4 game to disable the mods.