Hi @sega
In FME using AGOL, each user can only view the list of FeatureService that are created by that user or any items that are shared via Groups(with that user).
There is an Idea to add support for searching FeatureServices via ID, I would encourage to upvote the idea that we have here
https://knowledge.safe.com/idea/109212/allow-agol-feature-service-connection-via-agol-ite.html WORKAROUND:
1. Share the Item with a Group (where Editor is a member)
Create a Group with Editor as a member
Click on the contents you want to share--> Top Right (click Share) --> Edit Group Sharing --> Select the Group and click Ok
2. Use Esri ArcGIS Server Feature Service reader
Open the FeatureService, in WebUI, click on the required one
In the overview tab, on the right side towards the end of the page, there is a URL. Copy the URL with the Esri ArcGIS Server Feature Service reader