I tried to install kolab plugins in the "right" way, with composer and the roundcube plugin installer. However, I noticed that db tables for libkolab were not automatically created.
So I added the sql-dir parameter in plugins/libkolab/composer.json. like this:
"extra": {
"roundcube": {
"min-version": "1.6.0",
"sql-dir": "SQL"
}
}and installation worked correctly, db tables were created, and everything works.
Was I missing something of the above configuration is the correct one?