Is a 3rd party subscription okay for Mac App Store?

Hey there, first time posting here! :)

Just a simple question: For my desktop app, I have users sign in with an email/password combo that uses our own system (Firebase backend with no 3rd party logins). The app is free to use (requires an account) but you can upgrade to a paid tier for additional features. All payment and checkout goes through our website, which then gets authenticated/license checked within the application.

Is it okay for me to publish this app on the Mac App Store as is?
Or am I required to use the Apple IAP system for upgrades/subscriptions in this case?

Thanks!