As a shortcut to creating the templates, place the cache files in /vz/template/cache
devuan-2.1-x86_64-minimal.plain.ploopv2.tar.lz4
devuan-2.1-x86_64.plain.ploopv2.tar.lz4
Then follow the main README. You should see this output:
vzpkg list -O
devuan-2.1-x86_64 2019-12-14 19:24:21
devuan-2.1-x86_64-minimal 2019-12-14 19:22:02
You may then proceed to create your container:
prlctl create Devuan2 --vmtype ct --ostemplate devuan-2.1-x86_64
prlctl set Devuan2 --ipadd 192.168.5.101/24
prlctl set Devuan2 --nameserver 8.8.8.8