Importing .net users into firebase - firebase

Question

So to import into firebase, you need the hashing stuff to decode the password properly. We're using the microsoft owen security package from asp.net. I have a machineKey setup in the webconfig (I presume this is the hmac key I need to provide?)
<machineKey validationKey="<key>" decryptionKey="<decodeKey>" validation="HMACSHA256" />
and in the startup it's a simple
public void ConfigureOAuth(IAppBuilder app)
{
OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions()
{
TokenEndpointPath = new PathString("/token"),
AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
#if DEBUG
AllowInsecureHttp = true,
#endif
Provider = new SimpleAuthorizationServerProvider()
};
// Token Generation
app.UseOAuthAuthorizationServer(OAuthServerOptions);
app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());
}
To import into firebase, I'm using
(this is a dev DB user so it's ok that I'm showing the hash)
let userImportRecords = [
{
uid: 'afd698c4-4172-49f1-a6c4-77d175efbc1c',
email: '<usersEmail>',
passwordHash: Buffer.from('APwDZFRV6tnEREBsmECj2LMkgUZAqfOAb9/u0nMra5WrHgVG0F7ggFQABt0Qdtsw3w=='),
passwordSalt: Buffer.from('APwDZFRV6tnEREBs')
}
];
var admin = require("firebase-admin");
var serviceAccount = require("./socket-server/serviceAccountKey.json");
admin.initializeApp({
credential: admin.credential.cert(serviceAccount),
databaseURL: "<DB URL>"
});
admin.auth().importUsers(userImportRecords, {
hash: {
algorithm: 'PBKDF2_SHA256',
rounds: 10000,
saltSeparator: 16,
// Must be provided in a byte buffer.
key: Buffer.from('<webconfig machine decryptionKey key?>')
}
});
This will import but the password doesn't work. I'm assuming there's something wrong with how I have the salt and/or the hash key. I didn't see in the asp.net documentation where it's setting the key, but I know I have that machineKey setup so I presume this is what it's using. (we have another server that validates the tokens itself)
I'm fairly certain the algorithm and rounds are correct (pulled from documentation). I know the salt is at the front of the password hash, I think it's 16 bytes. But in this setup, do I leave the 16 bytes included in the hash or do they need to be removed? Did I even remove the correct amount of characters or do I need to throw this string into memory and extract the 16 bytes manually. I feel like this is super close. I just need to re-arrange my values.