JSFiddle - React, Tailwind, and code Playground

JavaScript

const ourScore = `EbAAdbBEaBaaBBdAccbeebaec`

const sortObject = (obj) => {
  const arr = []
  let prop
  for (prop in obj) {
    if (obj.hasOwnProperty(prop)) {
      arr.push({
        key  : prop,
        value: obj[prop],
      })
    }
  }
  arr.sort((a, b) => b.value - a.value)
  return arr
}

const getPlayers = (score) => {
  const scoreArrayLowered = score.toLowerCase().split(``)
  return [...new Set(scoreArrayLowered)].reduce((acc, item) => {
    acc[item] = 0
    return acc
  }, {})
}

const scoreCalc = (score) => {
  const scoreArray = score.split(``)
  const playersList = getPlayers(score)
  scoreArray.forEach((character) => {
    const keySave = character.toLowerCase()
    if (character === character.toUpperCase()) {
      playersList[keySave] = playersList[keySave] - 1
    }
    if (character === character.toLowerCase()) {
      playersList[keySave] = playersList[keySave] + 1
    }
  })
  const sorted = sortObject(playersList)
  return sorted
}

console.log(scoreCalc(ourScore))