Want to install the datapack on a pre-generated world? Follow these steps.
1. Download the datapack you want to install. I will be using my Spawner Craft Datapack
2. Click 'Singleplayer' in the main menu.
3. Click 'Create New World' in the world selection menu.
4. Click 'Data Packs' in the 'More' tab in world creation menu.
5. Now, drag and drop the datapack from your downloads folder to Minecraft. If done correctly it should show up like below.
* If the data pack does not show up follow these Troubleshooting Tips.
6. Now click on the pack icon to move the pack from 'Available' packs to 'Selected' packs.
* Repeat steps 5-6 for every data pack you want to install.
7. Now that you have all the data packs that you want installed you can click 'Done' in the data pack selection menu.
8. Finally you can now apply any optional settings you want to the world. After that you can then click 'Create New World' to generate the world with the selected data packs.