No, there are no such requirements. Some companies I have been working for use that on own servers. It works great. Just follow the link posted by @rbn@sopuli.xyz
As an addition: You may also know BigBlueButton - not an European but a Canadian alternative (maybe misplaced a bit in this community, but as some talk about Canada's EU membership, well, maybe not that misplaced -:)) BBB is a video software aimed at education, but you can use it also as 'normal' video tool.
And there is also Jami
Edit for an addition: If self-hosting isn't an option for whatever reason, you may consider joining Meet Coop, a cooperative using BBB. Their servers are in Canada and several European countries (you'll find them in the website).