Download OtakuDiscordAIO.theme.css from either the #download text-channel from the support server on discord or from here. Now open Discord with BetterDiscord installed, inside the Discord settings head to Themes and hit the Open themes folder button. Now paste in the downloaded file and fully restart Discord. Now the theme will update itself.
Preview (Guilds censored for privacy)
Join the Discord server for detailled changelog, support and anything else: https://discord.gg/6QkjVBk