Android apps need their own app password to access your information. If you use your normal password or your Fastmail two step verification password on an external account, syncing to an external service won't work and you will see a password error.
Setting up email
We offer detailed guides for the following email apps:
Calendars and contacts
Android does not support CalDAV or CardDAV, which are used to sync calendars and contacts. However, a workaround is installing a CalDAV or CardDAV sync adapter.
We have tested and recommend DAVx⁵, which is approximately $5. Once you have added your account in DAVx⁵, you can set up calendars or contacts in the app of your choice, and the changes will sync with Fastmail.
The CalDAV and CardDAV settings you will need can be found at our Server names and ports help page.
Be aware that any pre-existing contacts already on your device do not automatically get copied back up to Fastmail with the sync, so you will need to import them to Fastmail first.
Android does not support IMAP Notes natively, but you can use a third party app to sync your notes.