To download Meteor Client 1.8.9, follow these steps:

Since Meteor isn't an option for 1.8.9, here are the top-tier clients actually built for that version: LiquidBounce (Legacy):

A popular, open-source ghost client for discrete advantages.

To use Meteor Client safely, you must play on a modern version of Minecraft:

Meteor Archive (for versions 1.21.4 and up)