Simply clicking on the downloaded file (glibc-common-2.196.14.1-1.armv7hl.rpm) doesn’t do anything, so I suppose I have to install it in the terminal. The issue I’m facing right now is that I can’t access the Downloads folder while I’m in the Shell.
I read somewhere that clearing (rm *.0) the certs folder (/etc/pki/tls/certs) could help. Before that, I made a backup of the files inside (just in case). That didn’t make a difference, but maybe we can think of some way of transferring the required certificate/s manually? The newer versions of Sailfish OS had their own Certificate section in Settings just for that iirc.