Meteor login through different server - meteor

Question

I want to let my meteor users login through my react-native app.
I have one website built by Meteor/reactjs and the other is an App using android react-native and they both share the same Mongo database.
My meteor website uses bcrypt (meteor accounts-password), and my react-native app where I tried to use SHA256 and bcrypt so when I log in through my react-native app which is connected to the database, the hashed passwords do not match and I get an error.
I'm just getting really confused as to how to hash my react-native password to get it to the match the meteor users' hashed password. Any help would be great, cheers.
This is the front end
sendAjax = () => {
const m = encodeURIComponent(this.state.email);
const p = encodeURIComponent(this.state.password);
const hashDigest = sha256(p);
const requestBody = `email=${m}&password=${hashDigest}&mphone`;
//POST
fetch("http://**************/users/auth", {
method: "POST",
mode: "cors",
headers: {
"Accept": "application/json",
"Content-Type": "application/x-www-form-urlencoded"
},
body: requestBody
}).then(function (res, next) {
console.log("fetch request ", JSON.stringify(res.ok));
if(res.ok){
res.json().then(function (json) {
console.info(json);
console.info(json.verifystate);
if(json.verifystate){
Alert.alert("Login success");
Actions.leaderBoard();
}else{
Alert.alert("Login fail, please try again");
}
});
}else{
Alert.alert('Noted','request failed',[{text: 'confirm', onPress: () => console.log('OK Pressed!')},]);
next();
}
})
.catch(function (e) {
console.log("fetch fail");
Alert.alert('Noted','system error',[{text: 'confirm', onPress: () => console.log('OK Pressed!')},]);
});
}
This is my backend
app.post('/users/auth', function(req, res) {
loginData(db, req.body.email, req.body.password, function(result){
if(result == 1){
console.log("find the result!");
res.send({"verifystate":true});
}else{
console.log('cannot find it');
}
});
});
......
var loginData = function(db, email, myPlaintextPassword, mphone, callback){
var collectionUser = db.collection('users');
bcrypt.genSalt(saltRounds, function(err, salt) {
bcrypt.hash(myPlaintextPassword, salt, function(err, hash) {
var queryStr = {"emails.address": email, "services.password.bcrypt": hash};
collectionUser.count(queryStr, function(err, result) {
if(err)
{
console.log('Error2:'+ err);
}
callback(result);
});
});
});
};