This is what I am seeing when nginx is active instead of Apache 2.4:
For security reasons this script will only work with a new and unmodified Dokuwiki installation. You should either re-extract the files from the downloaded package or consult the complete Dokuwiki installation instructions
/volume1/web/dokuwiki/conf/local.php already exists
/volume1/web/dokuwiki/conf/users.auth.php already exists
/volume1/web/dokuwiki/conf/acl.auth.php already exists
The permissions on the folders were set according to your step by step instructions.
Concerning folder permissions, I have also now ticked the box at the bottom left in In File Station to apply changes to the folder, subfolders and files.
Well, I may have already copied earlier the data from the old DokuWiki (DSM 6.2) in the fresh install which may bring the error messages mentioned above. At the moment, when pointing to http://IPofSynology/dokuwiki/doku.php everything seems to be back on track and working!
The only problem I am left with is the error message under the administration console:
It seems your data directory is not properly secured. Please read https://www.dokuwiki.org/security#web_access_security
I guess this is normal behaviour based on the permissions set in your instructions on the folder dokuwiki/data. The access permissions should be fine though as http://yourserver.com/data/pages/wiki/dokuwiki.txt is not accessible.
Thanks again for your support