I’ve just configured some Velux Integra windows for a client.
As far as I can make out, there is no way to directly control them over TCP (for example).
They need a Velux central controller, called a KLF200
This has sets of contact closures for operating the 5 Velux window groups. (You can put as many windows as you like into each group)
I connected a bank of small relays to the contact closures to give control from Velbus and OpenHab2
I hope this helps.
FYi
Keyline don’t (as yet) have any kind of central controller, only RF remotes.