If you have downloaded the official .rbz or .zip file, follow these steps for SketchUp 2021:
If you encounter issues after installing the repack, use these quick fixes: download plugin 1001bit pro for sketchup 2021 repack
Go to View > Toolbars , scroll down to find 1001bit Pro, and check the box next to it. If you have downloaded the official
Instantly create staircase types, spiral staircases, escalators, and complex rafters. scroll down to find 1001bit Pro
Tools for creating terrain and site foundations. Understanding "Repack" Versions
If your file is in a .zip format instead of .rbz :
Unlike the freeware version, the includes over 40 specialized tools for architectural tasks.