The pier is an optional component, providing a very stable connection between the equatorial mount and a concrete pad to which it is attached with anchor bolts. The tripod that comes with the equatorial mount may be used instead, but it is not as stable as the pier. However if your scope will be on the move, for example as a demo unit, you’ll probably prefer to use the tripod instead of the pier.
The instructions are here. This topic is for discussing the instructions.