iclouddrive: add notes on ADP and Missing PCS cookies - fixes rclone#8310

Author: ncw

docs/content/iclouddrive.md

@@ -61,7 +61,7 @@ Enter a value.
 config_2fa> 2FACODE
 Remote config
 --------------------
-[koofr]
+[iclouddrive]
 - type: iclouddrive
 - apple_id: APPLEID
 - password: *** ENCRYPTED ***
@@ -78,6 +78,20 @@ y/e/d> y
 
 ADP is currently unsupported and need to be disabled
 
+On iPhone, Settings `>` Apple Account `>` iCloud `>` 'Access iCloud Data on the Web' must be ON, and 'Advanced Data Protection' OFF.
+
+## Troubleshooting
+
+### Missing PCS cookies from the request
+
+This means you have Advanced Data Protection (ADP) turned on. This is not supported at the moment. If you want to use rclone you will have to turn it off. See above for how to turn it off.
+
+You will need to clear the `cookies` and the `trust_token` fields in the config. Or you can delete the remote config and start again.
+
+You should then run `rclone reconnect remote:`.
+
+Note that changing the ADP setting may not take effect immediately - you may need to wait a few hours or a day before you can get rclone to work - keep clearing the config entry and running `rclone reconnect remote:` until rclone functions properly.
+
 {{< rem autogenerated options start" - DO NOT EDIT - instead edit fs.RegInfo in backend/iclouddrive/iclouddrive.go then run make backenddocs" >}}
 ### Standard options