Since you can get the plugin from different platforms, choose one and then follow the steps associated with it.
This is the simplest way to Download & Setup the plugin because of Fab's integration with Unreal Engine.
Open the product page: Fab - AQ Function Library - Sequencer
Buy the plugin
Open the Epic Games Launcher
Go in the section: Unreal Engine / Library / Fab Library
Find the plugin
Click Install To Engine
Select the engine version you want
Click Install
You will automatically receive the updates through the Epic Games Launcher.
On these platforms, the installation process is more manual
Open the product page:
Buy the plugin
Download the plugin
Here, you have the option to select which plugin version you want, but you probably want the latest.
Unzip the downloaded folder
Inside the folder, navigate to Unreal_Plugin
Select the engine version you want
Copy the plugin folder
e.g. "zip\AlexQuevillon_AqLib_Sequencer_1.0\Unreal_Plugin\UE_5.1\AqLib_Sequencer"
Paste it in the “Plugins” folder located in your Unreal project
e.g. "C:/Temp/UnrealProject/Plugins/AqLib_Sequencer"
If the folder does not exist, create it
If your project was open, close and reopen it
With this option, the updates are manual.
You will receive an email notification when the plugin gets updates, but you will need to go through the Install Steps to update it yourself.