Make updates to shared folders in Notes on iCloud.com
You can make updates to the contents in a shared folder All participants of the shared folder see any changes made to the folder.
In Notes on iCloud.com, select the folder you want to update in the sidebar.
If you have been invited to edit a folder but have not accepted the invitation, you need to click the link you received, then click Open in Notes. After you open the folder for the first time, it appears in the sidebar on iCloud.com.
Edit the notes within the folder.
When someone makes an update to a shared folder or to the notes within a shared folder, everyone sharing the folder sees the changes, but no one can see who made them. If an edit is made to a note in a shared folder, the timestamp below the note in the notes list shows the last time it was edited. If you are not currently editing a shared note, a yellow dot appears next to the note in the notes list when someone else edits it.
If you were invited to edit a folder using an email address or phone number that is not associated with the Apple ID you use for iCloud, ask the owner to resend the invitation using the correct email address or phone number. You can also follow the on-screen instructions to associate that email address or phone number with your Apple ID.