Thanks, @pfaffman and @Lilly, I guess I’ll be reinstalling then, following the instructions, at some point.
Thanks for the tip on the cert @pfaffman, but if it is going to be unsupported, then maybe not worth getting it working.
Meantime I’ll be on the .discourse.group hosting, shaking my fist at the cloud as to why something like slack integration needs to be at such an expensive tier.