You can authenticate to Nextcloud using a username and password.

It is recommended that the user has admin permissions.
If you are using Multi-Factor Authentication, you must create an app password for the user you want to use.

How to create an App Password
1. Click your avatar / initials in the top-right corner
2. Select Personal settings
3. Click Security in the left panel
4. Scroll to the bottom of the page to find the App passwords section
5. Type a descriptive name in the App name field (e.g. “SMART”)
6. Click Create new app password
7. Copy the generated password immediately and give to your administrator — it is only shown once