Anyone familiar with vacation plugin ment for roundcube out of office function.
https://plugins.roundcube.net/packages/gabtoth/vacation
I copied it to plugins directory, also made changes in roundcubemail/config.inc.php.
$config['plugins'] = array('vacation');
also made chown -R nginx:nginx to vaction folder, subdirectiories and files
Cannot understand why drivers needed for ?
Do I need something install to mariadb ?
Or something to do with composer.phar ?
Vacation button appear nicely in roundcube web environment, but when click button, displayed blank page.

I'm not familiar with roundcube and its plugins, but since it's a php application and you get a blank page, I guess this is due to some php error. Maybe the php version you're running is not supported by the plugin.
You can enable php logging and check the logs for details and/or ask the maintainer of the plugin.

Regards

Try to enable debug mode in Roundcube so errors are shown.

Edit the config.inc.php file and add:

$config['debug_level'] = 4;

Did it, resolved current issue. Thanks.
Vacation plugin appears correctly.

Next one when you activate plugin. It should send back message to sender with out of office info but it did'nt.
maillog displays error
Aug 12 15:36:07 xch2 postfix/local[23339]: 249B84036D94: to=<tigu@xch2.local>, relay=local, delay=1043, delays=1043/0.02/0/0, dsn=2.0.0, status=sent (delivered to maildir)
Aug 12 15:36:07 xch2 local[23343]: fatal: execvp /usr/bin/vacation: Permission denied
Aug 12 15:36:07 xch2 postfix/local[23339]: 249B84036D94: to=<tigu@xch2.local>, relay=local, delay=1043, delays=1043/0.02/0/0, dsn=4.3.0, status=deferred (temporary failure. Command output: local: fatal: execvp /usr/bin/vacation: Permission denied )


made with this guide http://acidicworld.blogspot.com/2018...roundcube.html
Seems like some user rights problem. Also tried to add different users postfix, current mailaccount "tigu@" etc. with command: chown -R username:username foldername

What gives
You didn't mention your distro, but if it's Centos like in the guide you've followed, it could be a SELinux permissions problem.

Centos 7 (Core) kernel 3.10.0-957.10.1.el7.x86_64

I changed vacation folder permissions many times, as root, as nginx, as mailuser, as postfix etc.

You should not change permissions arbitrarily. Besides the "make install" script is supposed to take care of the needed permissions.

Also you didn't mention anything about SELinux, or the permissions of the /usr/bin/vacation executable!