I’m a bit confused about how the cards and the signs relate. Some of the cards fit really well with their respective signs and they seem like equivalents of each other e.g. Justice and Libra, Death and Scorpio. Those two are very clearly aligned. But others seem to have nothing to do with each other- like Temperance and Sagittarius- and it’s more like the card is a lesson for the sign to learn. Sadge, an indulgent, wild, reckless sign needs to learn to be temperate. The Chariot looks to be teaching Cancer to gain control over their emotions so they can be channelled powerfully and productively- another lesson. I struggle to see any connection between Virgo and the Hermit other than introversion.
So yeah, I’m just a bit confused on how this is all supposed to fit together. Don’t know if anyone has any insight on this. Thanks.
Just for reference:
Aries = The Emperor
Taurus = The Hierophant
Gemini = The Lovers
Cancer = The Chariot
Leo = Strength
Virgo = The Hermit
Libra = Justice
Scorpio = Death
Sagittarius = Temperance
Capricorn = The Devil
Aquarius = The Star
Pisces = The Moon
It's because that tarot deck has nothing to do with actual astrology as it is known. Tarot is divination which uses cards as a tool. Palmistry is astromancy and uses astrology-like meanings too but has nothing to do with actual astrology.
Also I have 4 books on tarot and none associate the astrological signs with the cards, but have a small almanac that does. It has Cancer as temperance and Sagittarius as chariot. It has Aries as the sun and Scorpio as judgement. Virgo the hermit is described as...Truth is the key to the character of Virgo an earth sign with a tendency to see an ideal and settle for nothing less. The hermit too stands lofty and alone ready to shine his light of truth to all who seek it.
That's crap.
Look at the human design chart. Start with the fool at Aries... Hexagram 25. Divide the remaining 21 arcana into the 63 hexagrams... i.e. 3 per arcana, and you have your unification.
i don't think they do. not concretely like you put it yourself.
you don't really need it. Understanding the fool's journey to the end of a cycle of life the world [probably your saturn return] is enough.
Tarot is very subjective, so there is no perfect match with astrology. It's divination. There are no hard lines.
If a deck uses astrology in it, different decks will assign different astrological associations.
The astrology is supposed to enhance or expand the meaning of the card, but sometimes they seem arbitrarily assigned. Use astrology if it makes sense to you or enhances your possible meanings for the card.
Assigning astrology enhances my possible meanings of the card for that particular deck and also some of the knowledge may be carried towards cards other decks that don't have astrology.
That said, the assignments above look like the ones for the Thoth deck. If you want to understand why Crowley associated those placements to the Thoth, you can read his Book of Thoth.
He says the Hermit is associated with wisdom and attributed to highest form of Mercury. He also associates the light in the Hermit card with fertility in the most exalted sense (i.e. Sun as a creative force). Virgo is associated with fertility and Mercury is exalted in Virgo.
For Temperance, his explanation is more technical and complicated. 
He starts out saying the card is a complement to Gemini and Sagittarius is the opposite sign in the zodiac. Sagittarius means the Archer and the card is a picture of Diana the huntress.
These are the assignments Crowley made, but if it makes sense to you in another way, then use your own meanings.
If you asked me to relate those signs to the cards, Virgo could be associated with the Hermit since the Hermit is associated with gathering knowledge and wisdom, often in isolation (i.e. by reading books). Sagittarius could be associated with Temperance because of its expansive nature... people from opposite sides of the world (opposite elements) come together in a melting pot to create something bigger and better than themselves and expand their minds. Temperance is an alchemist.