Installing ProBuilder
Before you begin the following procedure, make sure that you have no errors in the Console window (in red text).
To install this package:
Open the Package Manager (in Unity's top menu: Window > Package Manager).
Enter ProBuilder in the search box.
Click ProBuilder in the package list (left side), then click the Install button in the package details (right side).
To verify that ProBuilder is correctly installed, open the ProBuilder toolbar (from Unity's top menu: Tools > ProBuilder > ProBuilder Window).
If you don't see the ProBuilder Window menu item, then ProBuilder did not install correctly.
Compatibility with Unity versions
This version of ProBuilder is only compatible with Unity version 2018.3 and later.
If you are running Unity version 2019.1, you must use the ProBuilder package version 4.0 or later.