I've seen cautions about taking it too literally from his writing (which a person has to have some degree of carelessness or preconceived notions or something to cause them to do so because he repeatedly explains not to) ...
But I found Fr Seraphim Rose's "The Soul after Death" to explain it quite well.
Please do NOT read the "Theodora" account and take it literally and assume that's "tollhouses" according to Orthodoxy.
It's really pretty simple. The demons are in the spiritual realm, which the soul is thrust into when it departs the body. The demons are still able to attempt to tempt, or threaten, or frighten, or suggest despair, or whatever they might think a good attack when one is dying. That shouldn't surprise us.
And our souls are formed by the lives we live, by our cooperation with the grace of God (or lack of cooperation), and so on. The less prepared we are, the less we look to Christ and the less like Him we are, the more trouble we may find when we come face to face with demons upon our death.
And there are angels also (though maybe not for someone opposed to God - I don't know).
It is referenced in Scripture, such as the "powers of the air" and so on.
Please please please forget wooden boxes in the sky or authority to judge being given to demons.