Contribution manager problems -- where to report?

Where do we report problems in the PDE contribution manager?

For example, in Processing 3.2.1 on OS X 10.10.5, my Libraries tab lists as available / compatible:

ToxicLibs 22

Installing (Install button) results in a temporary folder appearing in my /libraries, e.g.:

library5842271132355056316tmp/toxiclibs/

...and then a few seconds later it is deleted, with the message:

Could not find a library in the downloaded file.