Websites for online all-vs-all tournaments We have a small chess club with about 15 people, whereof about 6 - 10 people comes every week.
We play a blitz tournament where everyone meets everyone.

During corona, we do not meet physically, and the problem being that we don't know how to host the tournament where everyone meets everyone exactly once. Technical knowledge is very limited for some players, so managing the scoring manually is not an option.

Is there any website that offers this type of tournament? All we can see is where tourneys has x rounds and swiss pairing system.
Sadly I don't know of any such site, but I also manually conduct tournament in my small group( 12 members) via Lichess.

Just manually draw a Swiss tournament and setup a Discord for your club. announce the pairings and format and the players can decide the time of play with their opponents. collect the results and repeat the same for the next round.

Edit : Lichess is adding a Swiss tournament feature (source)