How to integrate account-js package to already existed mongo db?

I have a meteor app and want to migrate non-meteor app. I found account-js is compatible with the meteor account system. When I create new user everything works well but If I want to login with already existed user account-js methods does not work and I get unauth message everytime. How to login with already existed users by using account-js ?

   
const accountsPassword = new AccountsPassword({
  verifyPassword: (plainPassword, storedPassword) => {
    const hashedPassword = crypto.Hash('sha256').update(plainPassword).digest('hex')

    console.log('*****Verify Password*****')
    return bcrypt.compareSync(plainPassword, storedPassword)
  }
})

const accountsServer = new AccountsServer(
  {
    db: accountsMongo
  },
  {
    password: accountsPassword
  }
)

const accountsGraphQL = AccountsModule.forRoot({ accountsServer })


const schema = makeExecutableSchema({
  typeDefs: mergeTypeDefs([typeDefs, accountsGraphQL.typeDefs]),
  resolvers: mergeResolvers([resolvers, accountsGraphQL.resolvers]),
  schemaDirectives: {
    ...accountsGraphQL.schemaDirectives
  }
})

const schemaMiddleware = applyMiddleware(schema, permissions)

accounts-js utilizes an entirely different authentication mechanism than Meteor authentication system. accounts-js uses JWT tokens while Meteor uses unique hashes so it's not cross-compatible. I wrote a blog post about it which you can read here