How to Access NotePlan on Windows (or with a different Apple ID)?

You can use the web version to access NotePlan on Windows (or any other non-Apple operating system): https://app.noteplan.co

Which login should I use?

NotePlan syncs primarily through Apple's CloudKit, which is bound to your Apple ID. If you want to keep your devices in sync and use your existing subscription, pick the first option ("Apple ID Sign In") to sign into the web version (no matter how you subscribed to NotePlan or how you logged in initially).

Use the same Apple ID with which you are signed into your devices (see system settings of iOS or macOS and check which account you are using for iCloud).

Troubleshooting:

• If you have trouble signing in, see here. 
• If your notes and folders have a mismatch between web and your native devices, see here.