I am currently working on developing an application for the Hololens 1 using Unity and MRTK. I have been unable to get the air tap or any other input working in my application. The ring pointer for airtap does not appear in the application even though it works in the Unity Play Mode Input Simulation and other applications on the device. I tried it with the MRTK examples and even those did not work on the device.
Also I had to add the Tracked Pose Driver from the Player Settings to get the camera working properly but have not figured out how to get the application to accept gesture input.
Also tried the solution listed here: Why is 'air tap' gesture not working on HoloLens1 in my Unity/MRTK app? but that did not work. Will appreciate any guidance to solve this problem.
I finally got my project working after a lot of trying.
It turned out that initially, I had unknowingly configured the project to use XR SDK in Unity 2019 and thus had to configure MRTK accordingly. Thank you to Kevleigh for helping me with the issue here: https://github.com/microsoft/MixedRealityToolkit-Unity/issues/7850
While this did work for my example project, I couldn't get the main project to work with the same settings even after installing all the plugins.
Finally, I had to switch to Unity 2018 and I got the project working with MRTK 2.3 and the default configuration. So, while Unity 2019 did not work for me you can get it working with XR SDK as suggested in the above link.