The following site contains a link to downloads:
https://projects.apache.org/project.html?logging-log4net
That points to:
https://logging.apache.org/log4net/download.html
Which does no longer exist, probably because moved to (or a redirect has been removed):
https://logging.apache.org/log4net/release/download.html
The initial projects page appears to be generated from DOAP files.