Use the Forgot password flow whether you want to reset your password or your login keeps failing. It also tells you how your account was created.
First, make sure you are on the Login screen, not Create Account. Creating an account with an email that already has one fails.
Start here
Open the app and tap Login.
Tap "Forgot password? Tap to Reset".
Enter the email address of your Tarteel account and tap Reset Password. The app opens a screen that asks for a code and a new password. Before you type anything there, check your inbox: the email you receive says whether your account uses an email and password, Google, or Apple, or that no Tarteel account exists for that email.
If your account uses Google or Apple
There is no Tarteel password to reset, so ignore the code screen. Go back to the Login screen and tap Continue with Google or Continue with Apple.
If your account uses an email and password
The email contains a 6-digit code. It works for one hour.
On the screen the app opened, enter the code and a new password of at least 8 characters, then tap Complete Reset.
The app returns to the Login screen. Log in with your email and the new password.
No email? Check your spam folder. If the email says no account exists, try the other email addresses you use. You can request a new code once a minute, up to five times an hour. See also I did not receive the password reset or email verification code.