I don't know whether this is old or recent but I've never had this happen to me while installing voukoder, when I checked the CTT website to try to install it manually, the link sends me to a 404 github page (https://github.com/Vouk/voukoder/releases)
#Voukoder installation error
1 messages · Page 1 of 1 (latest)
Maybe Voukoder decided to go completely pay plan only.
yea i just downloaded it you have to do it manually