Papyrus Designer is an extension of the Papyrus modeler. In order to install it, there are three different methods.
2. Install Papyrus Software designer via the market place].
Papyrus vs. Papyrus SW designer versions
Papyrus SW Designer is an extension of Papyrus, but it is not part of the release train and released independently of Papyrus itself. Therefore, the version numbers differ.
Future 3.0.0 of SW Designer will compatible with Papyrus 6.0 and 7.0
Release 2.1.0 of SW Designer is compatible with Papyrus 5.0 and 6.0.
Release 2.0.0 of SW Designer is compatible with Papyrus 5.0 (for Eclipse version s 2021-03 and earlier)
A good starting point for Papyrus Designer are example models containing comments. These examples are available via File->New->Example, category "Papyrus" examples.