Processing App cannot install grafica

[jekoehler]

I am trying to install the grafica library at the 'Contribution Manager' of the Processing App on macOS (Sketch > Import library > Manage Libraries... >

Clicking on grafica to install version 1.9.1 gives an Error message (Fehler beim Laden und Installieren von grafica.)

There is also an error at the website https://jagracar.com/grafica.php. When I click the link (https://raw.github.com/jagracar/grafica/master/releases/grafica.zip) to the latest library version I get an error:

Error 503 hostname doesn't match against certificate

It seems there is an invalid certificate which denies downloading and installation.