Serif have just released the latest update to their Affinity Publisher beta for Mac / Windows. You can read about it here.
If you have the previous version installed, it’s an auto-update that should pop up when you initiate Publisher (from a fresh start).
If you’ve haven’t yet tried it, you can sign up for the beta on the above linked webpage.
Hmm 
Anyone else having trouble getting it to download?
Seemed to install OK and opened pretty quickly after the update. I haven’t spent too much time with the update yet, but so far, so good.
I had a couple of HS security updates pending so I did those, with their corresponding restarts. When I tried the APub update process after that, it worked first go and installed smoothly.