ATC is used to working with military aircraft without ADSB since it's been the status quo (and keep in mind that ADSB is not required on aircraft in general, although the set of airspace situations in which it's required has been expanded over the years to become a de facto near universal mandate). But the FAA doesn't like it, which is why they set the deadline for the Air Force to install ADSB, which the Air Force missed.

Military aircraft on military maneuvers don't deal with FAA ATC, the military has its own controllers. It's mostly an issue when they're operating near civilian airports (or the many, many military facilities that share an airfield with an airport). There are still adverse safety impacts to the lack of ADSB on many military aircraft, in that it defeats things like TCAS.

Actually this topic is slightly complex and I think a lot of people have misconceptions, so let's lay it out. These rules have gotten stricter and stricter in recent years.

1. ADSB is not required. Meaning, there is no universal requirement that aircraft be equipped with ADSB, and plenty of aircraft still legally operate without.

2. ADSB is required in class A, B, C, in many cases in class E, and within the "Mode-C veil" surrounding major airports.

3. ADSB is required in any case where a transponder is required, for those edge cases that are not included in the above.

4. The result is that the areas in which you can legally operate without ADS-B are mostly limited to low altitudes in rural areas. Of course, this encompasses a large portion of hobby aviation especially, but not very much commercial flight.