You can, but it is not recommended.
A mixer tap works by accepting a cold water line and a hot water line, and then mixing them together to get a desired temperature.
The adjustment is made by regulating, either more or less, hot or cold water into the mix.
When you plug the HOTTAP hot water line into a mixer tap, the mixer tap can then reduce the water flow of the HOTTAP below the minimum operating flow, and cause the HOTTAP to turn off. And when the HOTTAP turns off, you need to fully turn off the flow (from the tap) and then open it back up, in order to turn the HOTTAP back on.
The best thing to do is to get a dedicated tap just for the HOTTAP.