curl -X POST https://api.dropboxapi.com/2/sharing/add_folder_member \
--header "Authorization: Bearer <ACCESS_TOKEN>" \
--header "Content-Type: application/json" \
--data "{\"shared_folder_id\": \"<SHARED_FOLDER_ID\",\"members\": [{\"member\": {\".tag\": \"email\",\"email\": \"<EMAIL_ADDRESS_TO_INVITE>\"},\"access_level\": {\".tag\": \"editor\"}}],\"quiet\": false,\"custom_message\": \"Code examples\"}"
<ACCESS_TOKEN> should be replaced with the OAuth 2 access token.
<SHARED_FOLDER_ID> should be replaced with the shared folder ID, e.g., as returned by /2/sharing/share_folder or /2/sharing/list_folders.
<EMAIL_ADDRESS_TO_INVITE> should be replaced with the email address of the user to invite. Also, members is an array and can contain multiple users.