How do I use my Apple ID to sign up for Obimy?

While the developer of the app is the best and THE authoritative source, a quick perusal online makes it appear that Obimy might have implemented Sign in with Apple. (SIWA)

You can read more about that very capable privacy-protecting feature here:

What is Sign in with Apple? - Apple Support

However, be careful to never, EVER provide your actual AppleID password to ANYONE / ANYTHING (other than an Apple web site).

The SIWA sign-up process hides your AppleID and if desired, your actual e-mail address.

If you are experiencing any difficulty with third-party apps or a specific website then please contact the app developer or site publisher/host directly --> How to contact an app developer - Apple Support