Add broth and chicken: Pour the chicken broth into the crockpot and add the raw chicken breast, diced onion, minced garlic and drained beans. Stir everything together so the chicken is mostly covered by liquid.
Season the broth: Sprinkle in the Cajun seasoning, soy sauce, rice vinegar and black pepper. Give it one more stir to distribute the seasoning evenly.
Cook on low: Cover the crockpot and cook on low for 5 to 6 hours. The chicken is ready when it shreds easily with two forks.
Shred the chicken: Remove the chicken breast to a cutting board and shred it using two forks. Set it aside briefly while you prep the remaining ingredients.
Add sausage and spinach: Stir the sliced sausage and squeezed-dry spinach into the crockpot. Return the shredded chicken to the pot as well.
Melt in the cream cheese: Add the cubed cream cheese and whisk it into the hot broth until fully melted and smooth, about 10 minutes with the lid off on low heat.
Taste and adjust: Taste the broth and add more Cajun seasoning, salt or black pepper as needed. The broth should taste rich and slightly smoky.
Serve: Ladle the hot soup into bowls immediately while the broth is thick and steaming. Serve with warm biscuits or crusty bread if desired.