You can manage your mods in Baldur's Gate 3 by opening the game and accessing the Mod Manager from the Main Menu.
Once you have entered the Mod Manager, you can choose your favorite mods and then click the Subscribe button below the mod. Once downloaded, the mod will now be highlighted green and say "Subscribed."
Additionally, you can manage your mods using the Installed tab at the top of your screen. Here, you can enable or disable mods using the checkbox next to each mod as well as uninstall and unsubscribe from them using the panel on the side of your screen.
If you have any difficulties, please feel free to open a ticket!