V3.6.13 can't install campaign manager

when I try to install campaign manager (which somehow disappeared in the last update) following instructions here:

Install through phplist
Install on the Plugins page (menu Config > Manage Plugins) using the package URL
and input that URL into the Plugin package URL and click install, I get the error message:
Error: Invalid plugin package

I solved the issue by uploading the files and extracting into phplist. The automated method did not work for some reason.