No, sorry for not specifying, I installed Discourse through the turnkey method that YunoHost uses.
GitHub - YunoHost-Apps/discourse_ynh: Discourse package for YunoHost · GitHub is the YH repo for Discourse integration.
I followed the plugin install instructions at GitHub - YunoHost-Apps/discourse_ynh: Discourse package for YunoHost · GitHub
I’ve created an issue over there, because I’m guessing installing an official plugin should be fairly simple, and it’s their method will be incorrect in some way. Internal server error when trying to use official Shared Edits plugin · Issue #151 · YunoHost-Apps/discourse_ynh · GitHub
Thanks you your help anyhow.
P.S. There is no ./launcher with the install via YunoHost.