Synology's NAS system used to provide a DokuWiki package in their package manager. Since the DSM 7.0 release, this is no longer the case. Instead you need to manually install DokuWiki using the Web Station app.

Synology does not currently provide a package for installing Dokuwiki on the Diskstation under DSM 7.
This procedure should help to install Dokuwiki on a Synology Diskstation running DSM 7.

On DSM:
Package Center: Install Web Station

• Install Apache 2.4 via the Package Center
  Hint: go to Web Station Status Panel and click the Arrow in Management Column, this will bring you to the Apache Install Package in Package Center
• Install PHP 7.4 via the Package Center
  Hint: go to Web Station Status Panel and click the Arrow in Management Column, this will bring you to the PHP Install Package in Package Center

In Web Station this will create a customized Profile under “Script Language Settings” with name 'user-defined'

• Edit the Profile and activate the following Extensions:
  • bz2
  • gd
  • ldap
  • openssl
  • pdo_sqlite
  • zlib

Save the settings!

On your PC: Download DokuWiki: https://download.dokuwiki.org/

On DSM:

• Go to File Station
  • Select left the Web Folder
  • Upload the downloaded Archive from DokuWiki (TGZ)
  • Right Mouseclick on the Archive in File Station and select Extract… → Extract here
  • Do the same with the new File (TAR)
  • You have now the Folder “dokuwiki” in your Web-Folder
  • Delete TGZ and TAR File

• Go to Web Station and select “Web Service Portal”
  • Edit the default server
    • If installed Apache: Httpback-end server: select Apache
  • PHP: Select the created Profile (Default Profile 7.x)

• File Station: Setup Permissions for Folders
  • Go to Web Folder
  • Select dokuwiki Folder
  • Right Click on data Folder
    • Properties → Permission → Create:
      • User or Group: http
      • Select Read and Write
      • Click Done
      • Click Save

Repeat this steps for folders: dokuwiki/conf, dokuwiki/lib/plugins and dokuwiki/lib/tpl

Go to: http://<IP_of_your_Synology>/dokuwiki/install.php

Done.

There are several possible ways to switch from a package installation to a direct installation.

• copy the directory “dokuwiki” to another location outside the “web” folder
• uninstall the package “Dokuwiki” via the package manager
• copy the “dokuwiki” directory back to the “web” folder
• upgrade to DSM 7

Some users report problems with permissions after this procedure: User Forum: Dokuwiki package no longer supported in Synology DSM 7. If this problem occurs, a complete reinstallation is recommended.

This procedure is taken from User Forum: Manual install of Dokuwiki in a Synology NAS running DSM6.2
It is the same procedure as for a complete new installation. Only the backup of the data is added and the procedure for this is described.

1. To be extra save; copy the nas/DokuWiki folder from your Synology to a other location.
2. Delete the DokuWiki package with the Package Center.
3. Upgrade to DSM 7 (see instructions on the official Synology site)
4. Go to Webstation in DSM → PHP Setting (scripttaalinstellingen in my native language) → Create/Make → Profile name: Dokuwiki → Profile description: Dokuwiki → PHP version: PHP 7.4 → enable Extensions: bz2, gd, openssl and zlib and click Save/Ok.
5. Go to Webserviceportal (still in Webstation) and choose for HTTP back-endserver: Apache HTTP Server 2.4 and PHP: Dokuwiki (PHP 7.4.) → Save.
6. copy dokuwiki folder back into web directory

• Dokuwiki package no longer supported in Synology DSM 7
• Manual install of Dokuwiki in a Synology NAS running DSM6.2