I admit I am completely new to this modpack but no matter how many or how few dimlets I use (even when following the listed dimension guides here) when I place the Realized Dimension Tab into the Dimension Builder I am given the Too many dimensions! message. I don't know exactly what I am doing wrong here...

If it matters at all I am using the modpack through the FTB Skyblocks Evolved modpack.

Are you on a server? Then your server admin has configured RFTools with a maximum number of dimensions per player

I am not on a server but I suppose that could still be the problem? I will have to try and find how to change that...

You can find the setting for this in the rftools config. MaxDimensionsPerPlayer or something

Is this configurable via roles or by player in some way? Say you want some players to have more possible dimensions than others.