2.1 Loading Forge

Loading Magit doesn’t cause Forge to be loaded automatically. Adding something like this to your init file takes care of that:

(with-eval-after-load 'magit
  (require 'forge))

Or if you use use-package:

(use-package forge
  :after magit)

By default Forge adds some bindings to Magit keymaps and menus, and sections to Magit buffers. If you would like to prevent that, you have to set forge-add-default-bindings and forge-add-default-sections to nil before magit (not just forge) is loaded.