Nest Binding Communication Error

Hi, I’m a first time user trying to integrate my Nest Doorbell into openHAB. I am following the instructions given for Nest Bidings ([Nest - Bindings | openHAB)
and just created my SDM Account thing. At this point it should be live but I’m getting an error:

COMMUNICATION_ERROR

Exception in oauth communication, grant type authorization_code: org.eclipse.jetty.client.HttpResponseException: HTTP protocol violation: Authentication challenge without WWW-Authenticate header

This is the log file:
Processing: openhab.log.1…

Any ideas what I’ve done wrong?

Platform: NUC i5/8Mb/125Gb
OS: Windows 10
Java: Zulu Java 11.0.13
openHAB: Version

This is the log file:

2021-11-23 13:55:43.758 [INFO ] [.core.internal.i18n.I18nProviderImpl] - Time zone set to ‘Europe/London’.
2021-11-23 13:55:43.789 [INFO ] [.core.internal.i18n.I18nProviderImpl] - Location set to ‘51.21006490174292,0.30416965309996163’.
2021-11-23 13:55:43.789 [INFO ] [.core.internal.i18n.I18nProviderImpl] - Locale set to ‘en_GB’.
2021-11-23 13:55:48.038 [WARN ] [org.openhab.core.net.NetUtil ] - Found multiple local interfaces - ignoring 192.168.0.20
2021-11-23 13:55:57.051 [INFO ] [.core.model.lsp.internal.ModelServer] - Started Language Server Protocol (LSP) service on port 5007
2021-11-23 13:55:58.816 [INFO ] [org.openhab.ui.internal.UIService ] - Started UI on port 8080
2021-11-23 13:55:59.332 [INFO ] [ab.ui.habpanel.internal.HABPanelTile] - Started HABPanel at /habpanel
2021-11-23 13:56:00.300 [ERROR] [oauth2client.internal.OAuthConnector] - grant type authorization_code to URL https://accounts.google.com/o/oauth2/token failed with error code invalid_grant, description Bad Request
2021-11-23 13:56:04.159 [INFO ] [e.automation.internal.RuleEngineImpl] - Rule engine started.
2021-11-23 14:54:24.415 [ERROR] [oauth2client.internal.OAuthConnector] - grant type authorization_code to URL https://accounts.google.com/o/oauth2/token failed with error code invalid_grant, description Bad Request