For Mobile:

Step 1: Find Games Folder in your internal Storage/External Storage, in Games Folder Find com.mojang > minecraftworlds folder.

Step 2: Open Downloaded World and find GGNCXbqqAAA= folder, just copy this(GGNCXbqqAAA=) folder and paste here(minecraftworlds) folder.

For PC:

Search minecraftworlds folder from search option. and copy GGNCXbqqAAA= folder in minecraftworlds folder.