Which file and which version are needed
First, look at the title of the edition in the game. This order applies to Minecraft: Bedrock Edition. Bedrock add-ons use resource and behavior packages: the former are responsible for the appearance, the latter can change game actions and content. Instructions for another edition do not replace the requirements of the selected supplement. In the package card, find the supported version and a description of the changes. For the first test, choose one clear function, such as a new item, so you can immediately notice the result.
How to enable an add-on from Marketplace
After receiving the Add-On, open Play and create a new world. In the settings, find Resource packs or Behavior packs, select the desired package on the Available tab and click Activate. Then create the world. For an existing world, click the pencil icon next to it, open the appropriate packages section and activate the add-on before launching. Just because a package is in the collection does not mean that it works in every save.
How to check the import of an individual package
The official documentation describes importing .mcpack on supported devices by opening the file in Minecraft. After the successful import message, check the list of packages in the world settings. The .mcworld file imports a world, so look for the result in the list of worlds. If there is an error, write down the exact message and compare the author's requirements with the established edition. Don't rename an arbitrary archive into a package expecting that this will fix its contents.
Why is the add-on not visible in the world?
Check three things in turn: the import is complete, the package is activated specifically for this world, the test corresponds to the promised function. To experiment, make a copy of your valuable save and start with one addition. If it works separately, connect the next package and repeat the same check. This makes it easier to detect conflict. The absence of new mobs immediately after logging in does not necessarily mean a breakdown: read the conditions for appearance in the package description.
Sources and checks
Guides are automatically translated from Russian; interface labels may differ. The Russian edition is the original.