Important: You will need to enable the following settings in your bot's control panel: enter your "developer control panel" and select a bot, then go to the "bot" section-in here, enable "presence intent", "server members intent", "message content intent" - and hit "save".
All of the central class managers are classes that are filled with static methods that are a part of the discord_core_api namespace, they are as follows:

discord_core_api::application_commands

discord_core_api::auto_moderation_rules

discord_core_api::channels

discord_core_api::event_manager

discord_core_api::guilds

discord_core_api::guild_members

discord_core_api::guild_scheduled_events

discord_core_api::input_events

discord_core_api::interactions

discord_core_api::messages

discord_core_api::reactions

discord_core_api::roles

discord_core_api::stage_instances

discord_core_api::stickers

discord_core_api::threads

discord_core_api::users

discord_core_api::web_hooks

Each of the functions in this library takes an argument that is of a type who's name is derived from the function-for example, the data structure that gets passed into discord_core_api::guilds::getGuildAsync() is discord_core_api::get_guild_data.
Most of the functions in this library are discord_core_api::async, meaning that they return a value of type discord_core_api::co_routine<discord_core_api::co_routine::return_type>, which you call discord_core_api::co_routine::get() on to retrieve the returned value, and to suspend the current thread in the process of waiting for it. alternatively, you have the option of leaving the task's completion up to the background thread that is handling it, by not calling discord_core_api::co_routine::get().