My monitor is Dell U2419H , does it fit with it or not? I see that it does not come with a mount adapter, but it says that it is compatible with my monitor.

Likely not, since you can clearly see from the photos that the monitor misses the required holes to attach the speakers to. The controls are on the bottom of the monitor, whereas the older monitors have the controls in on the front panel. I recently bought the Dell U2718Q and it's a similar model. The speaker neither fit directly on the monitor nor on the stand with the packaged stand adapter. I engineered an alternative from the plastic parts of the adapter. :-)

According to Dell HP, this soundbar was "developed" for your monitor. I also relied on this information for my monitor and am very satisfied. Greetings