A First glimpse
Check in your data directory for the
The logging level can be changed .
You may find useful to see in the forum some pages [f1,f2].
You may search for "+owncloud +app +log +file +audit".
Since some finding refer to the payment version, you may search for nextcloud solution too.
A second not definitive glimpse
Owncloud seems to allow a level of Logging and Auditing ...
Logging and Auditing
Visibility of all file sharing is critical for maintaining regulatory and judiciary compliance. The ability to maintain an audit trail and set alert conditions ensure IT will be able to support the business requirements of compliance while providing enhanced productivity for employees.
Not only does ownCloud allow IT to control each user’s permissions, but it also enables a full audit trail - allowing IT to understand how, when and where data is accessed and shared. Admins can log account level activities such as logins to ownCloud as well as what users do with files on the server. This provides basic information needed for compliance reporting and auditing of ownCloud usage, and the tools to actively follow file sharing activities.
Even if it seems only to log user actions and actions on files. For this it exists a graphical app too , even if available for the enterprise version only.
You stated that you want to share the file with the "share link feature" that allows :
With ownCloud X (10.0), we introduced the ability to create multiple public links per file or folder. This offers a lot of flexibility for creating different kinds of share links for a single file or folder, such as different passwords, expiry dates, and permissions.
So you should be able to have a log for each password.
You may try.