Ok, here's the math.

US Population: 327.2 million
77.4% of those are over 18, taking the number down to 253.3 million 93% are citizens, which means there will be a total of 235.6 million getting the freedom dividend That's 235.6 million times 12,000 per year, so the cost is 2.827 trillion dollars per year. We'll even round that up to 3 trillion.

The overlap with welfare saves 500-600 billion
Social Security overlap (not mentioned on the page I linked as it's not updated, his proposal used to be ages 18-64) saves 800-900 billion

Cost is now down to around 1.6 trillion

A 10% VAT will give 800 billion per year
The economic growth that comes with UBI would give back 400-600 billion
100 billion from carbon fee
and now comes the savings you mentioned, which are from "health care, incarceration, homelessness services" and other similar things, which gives 200 billion

There's a few other sources Yang plans to use that I didn't list here, since they're not as big.
I don't personally know how accurate these numbers are, so if you want to argue that one of these things won't give nearly as much as I stated, I can't argue. But my point is, these are the numbers Yang is using. Whether accurate or not, they do add up to the cost, which means his plan does not involve printing money.