Just so you know, Filipe is joking. What he explained is kind of a running joke on the Blockland forums.
To be fair those users on the first page were joking because your group shares the same name as the paid service on a free-to-play game called ROBLOX. ROBLOX and Blockland are two very different games that are compared way too much (and several forumers play ROBLOX themselves, myself included).
On-topic though, I wish you the best of luck running your building group. FYI, Blockland actually has built-in clan tag support, for prefixes (placed before your username in the chat) and suffixes (placed after). These both have a 4-letter limit, and can be found in the same menu you customize your in-game avatar in: the Player button on the main menu.