First place to start is MOS Oracle Support Document 274526.1
https://support.oracle.com/epmos/faces/DocumentDisplay?id=274526.1
Go to patch 6880880 that brings you to the download page.
There is no wget.sh script to download, so that is what we will create ourselves.
Select the correct version to download, and then Right-click the download button and copy the hyperlink.
Paste the hyperlink in a fresh notepad, and enclose it with quotation marks:
"<link>"
Add the following in front, to make your command:
wget --http-user=<MOS-user> --http-password=<MOS-password> --no-check-certificate --output-document=latestopatch.zip "<link>"
Paste this in your Linux session and your opatch is downloading.