But what gives him the authority to direct how the money is spent? I'm still not getting it.
Well, consider. Suppose (because of shitty and unclear legislation) it is unclear whether or not Congress has directed the spending of money for the benefit of (say) Ukraine, but other laws actually prohibit giving a corrupt government one fucking penny.
A President then would find it impossible to both spend the money but not spend the money. So, at least in theory, he must then make some choices. He could determine to NOT spend the money at all in order to comply with that other law.
For example, the EO on gender-affirming care will fall flat on its face because it violates Subpart B (iv) of Section 1557 of the ACA.
Maybe not; instead, perhaps that provision will be determined to be a denial of a Constitutional right to equal protection of the law. A President isn’t allowed to administer any law which violates the Constitution.
His order freezing funding violates the Impoundment Control Act.
Not always. Again, it depends on the individual facts. Alternatively, it may be that the impoundment control act itself oversteps the bounds of what the Constitution allows Congress to do.
His buyout order needs approval from Congress, that's why Clinton asked for Congressional approval in 1995 to conduct the federal buyouts.
Again. I don’t know. But he acts as he sees it as his duty to act.
That example may be a fair case for judicial review of his action. So, he acts as he sees necessary and awaits that eventual judicial scrutiny.
In that case, it’s not just a lower court issuing a pause or a stay. Ultimately, it’s likely to be a SCOTUS decision.