preview timeline widget on browser and generate scrom file instead .cpt

Your first question: what do you mean? You don't see a preview of the slide where you inserted the Timeline? Can you tell which browser you used? 

Second question: You are very new not only to Captivate but probably to the eLearning/LMS worlf. I will try to explain. At this moment you are editing 'raw' Captivate file, and when saving that has indeed the extension cpt. When your course is finished you need to PUBLISH the course to a format that makes it possible to upload to either a webserver or a LMS. Such a published output is not one file but a folder with subfolders. BTW the cpt file is in fact also a zipped folder (just like a PPT file).  

If you need to upload to a LMS you'll often need to publish a 'SCO', which is an output folder which also includes all files necessary to allow the transfer of data between the course and the LMS. To create such output you need to activate Reporting in the Quiz Preferences. You find Preferences under the Edit menu if you are on Windows, or the Captivate menu if you are on Mac.