Install specific version on ubuntu

Hello,

Yes, Ubuntu/Debian versions are available since 10.15.0 and onwards.
You just need to change /etc/apt/sources.list.d/kaltura.list
deb [arch=amd64] http://installrepo.origin.kaltura.org/repo/apt/debian-$DESIRED_VERSION kajam main
For instance:

deb [arch=amd64] http://installrepo.origin.kaltura.org/repo/apt/debian-11.3.0 kajam main

As to the other question, yes, you can look at: https://wiki.debian.org/HowToSetupADebianRepository#APT_Archive_Mirroring_Tools

for info as to how deb repos can be mirrored.