Amber's standing military forces are at fairly low peacetime levels. Amber-the-nation isn't huge; there are maybe half a million citizens. Something like 3000 troops in the military during peacetime, split roughly equally between the navy and the three important stations in the realm: Amber city itself, mountain passes in the far north, and the main passes in from Arden. Due to the longer lifespan of Amber normals compared to Earth, there's a much higher percentage of the population with experience, but those wouldn't be called up unless Amber was directly invaded. Amber is in possession of The Great Equalizer, a.k.a. gunpowder, so all the engagements in living memory have been pretty one-sided.

Modern Earth numbers, for comparison: most nations don't have active duty troops over 1% of their population; Israel's in the 2-3% range and North Korea is close to 5%. US mobilization in WW2 was somewhere around 12% and is currently under around .5% now.

Big things like the historical throne war and black road war in the books involve troops raised from near-shadow. (That's why losing 20,000 or so troops didn't cripple Amber). Note that recent in-game military issues haven't been using Amber's troops either.

Arden rangers are irregulars, not counted as part of the army. There may be a few hundred of them. As above, their numbers may be enormously boosted by local and foreign recruits during important events if one of the royals is directly overseeing them. Likewise, the navy stats are for the ones stationed in Amber city harbor. Shadow patrols of the trade network are conducted by allied shadow navies.

Military intelligence / spies: are a gestalt of info from the formal military, the private sources of the royals, information from trade interests, and information from shadow allies; so the numbers aren't publicly known. "Special ops" are what the royals do themselves; those groups are formed at need, using local and shadow recruits, and disbanded afterwards. So if, say, Malserrin builds his air force, they'd be considered a special group unless/until the King makes it officially part of the standing military.