Once the application has been downloaded, subsequently, the following steps should be followed to register for the service:
Step 1. Please enter your Email and choose either of the one Sign Up options for Sign Up. Click on Continue button on the home page..
Step 2. Complete the required information ("name, email address, mobile number") and proceed with the sign up process..
Step 3. Enter the activation code you received in your mail to activate the account.
Step 4. To set up your Sign In passcode, type in your 4-digit code and confirm it correctly. Once you've done that, you'll be ready to register..
Step 5. Re-enter to confirm the correct passcode. Once the passcode  matched & the device is successfully registered.
Step 6. Select your account & enter 4 digit passcode to sign in.
Step 7. After entering the activation code you received in your mail you can also choose for desktop Signin to continue.
Step 8. You can either choose desktop signin with account access code or with mobile signin to get into the services.
Step 9. Choose the MTDVAT Service & make MTDVAT Authorisation Setup.
Step 10.  After your account has been created, sign in to the account. Each time you SIGN IN you will be asked to enter the sign in "4 - digit passcode". 

RoadMap for Sign Up:  Open the application -> Enter your "e-mail" and choose either of Sign Up options -> Then fill in your name, email address, mobile number and proceed ->  Now, enter the activation code received your email -> Setup a passcode by entering twice ->  After your passcode is matched, the device is succesfully registered.

Here's a video on how to Sign Up for MTDVAT: