I registered but I’m not being allowed to build. Please can someone help 
If you type in chat, does your rank appear as member?
If it doesn’t ask a member of staff to sync your permissions.
If it does, you may be trying to build somewhere you’re not allowed to (e.g. map spawns)
Maybe you were trying to build in Big City, /warp cspawn will take you to creative warp and /map will take you to the realtime map for you to look for a good location to build your new city!
So yeah, pretty much what octo said, but a bit more long xD