I am confused how this particular group is labeled "right wing". My understanding of the label, right wing, is strong support for the government in power and the police. The label would fit the Proud Boys with the additional labels of extreme and militant. This militia group that was planning the attack is strongly anti-government and think of the police as oppressive jack-booted thugs (pretty much the same position on authorities as antifa has). They could rightly be labeled as revolutionaries or just plain nuts.
They were following the directions of their spiritual commander and planning an attack on those "oppressing" the right.