https://www.tacview.net/documentation/dcs/en
Using Tacview with DCS World is straightforward. In most of the cases, this is a smooth and fully automated process. When you install Tacview, all the necessary scripts and settings are automatically installed so you are ready to record your first flight right away!
However, they are some rare cases where Tacview exporter cannot do its job properly. Please, read carefully the following guide to know how to get the most of DCS World and Tacview and to know how to prevent or fix potential issues.
If you can’t record any flight in multiplayer, make sure first that you can record single player flights. It is possible that your problem is coming from the multiplayer host. But it may be coming as well from your local setup!