Every time I try, it goes to a broken page telling me the server esotericsoftware.com did not accept the certificate. Launcher keeps telling me to re-download and install spine because it's out of date, but... that's the problem.

The license is Spine Professional.

Nope, not using a proxy as far as I know. Thanks for the link but it isn't my problem; I already have Spine (professional) installed and have been using it fine for some time, am just now attempting to download the update it keeps pushing but once it downloads the update it tells me to re-download and reinstall Spine because "launcher is out of date".

However, on the license page, upon trying to download the launcher, it gives me a broken page.

Alright, sent in an email.

I'd just like to update, for others' future reference, that switching browsers worked. Safari was the problem (some sort of additional security handshake?). Successfully downloaded using Firefox and am finally on the newest version. (:

Thanks for the help.