Legacy Plugins
The term Legacy Plugins refers to plugins installed without involving the Plugin Manager or any other part of the OpenCPN core. This was the only way to deploy plugins before the new Plugin Manager in 5.2.2.
Packages was deployed as NSIS installers in Windows, .img packages on MacOS and Debian .deb packages on Debian/Ubuntu. There was no flatpak legacy plugins. Users installed these packages in the same way as OpenCPN and other programs are installed.
The support for legacy plugins was removed in version 5.8.0; from this point the Plugin Manager is the only way to install plugins.