Egosoft community account
To use any of the games online features, like the new paintmod that any customer gets for free for just registering their game, you need to set up an account on www.egosoft.com for the online community (same as your forum account!).
Paintmods:
How to register:
For the Steam version: Select the "Register" button from the "Online Features" menu of X4: Foundations and linking should happen automatically after login or creation of a new account. As an alternative, or when using the GOG version, log in to your egosoft.com account or register a new account and go to the "Game Registration" section in the top left corner. Then click on "Sign in through Steam" (or "Update via Steam" if you are already linked) or enter your GOG serial key. You can find the GOG serial key from GOG Account -> Library -> X4 -> More -> Serial keys.
How to apply the paintmod
Right click on any of the ships you want to apply the paintmod to and select "REDESIGN" from the list of actions. There will be three tabs with the rarity categories of mods. The bonus one for everybody is in the ADVANCED tab, the rarer one for CE pre orders is in the EXCEPTIONAL category.
Can not find paint mods in game?
If you do not see your mods listed in game in the REDESIGN action of one of your ships, after activating the game in the online community, try logging off and on again (or just restart the game, same effect).