By default on Windows 10, .Net 3.5 is not enabled.
OpenEdge 10.2.B.x is certified only on .NET Framework version 3.5. The OpenEdge 10.2B installer has the active .NET versions bundled, but during the installation, this message window for the bundled OpenEdge version will be presented.
Choose “Download and install” when prompted for .NET 3.5 installation during the installation and continue with the installation.
For further information review the "
Install the .NET Framework3.5 on Windows 10,Windows8.1, and Windows8" at Microsoft's Website. This information is attached to this Article as a .pdf for your convenience.