when I try to install extensions I get this message:
“Your KNIME installation directory seems to be read-only,
maybe because KNIME was installed by a different user, e.g.,
the system administrator. Installing extensions or updating
KNIME without write permissions may cause problems. Do you
really want to continue?”
Can you try and write into the installation directory and see what it say. Or can you try and download the ZIP-file containing KNIME and just unpack that to your local system in a folder where you have write access. If indeed you are on a Windows machine.