Congress.gov is a free website maintained by the Library of Congress, and provides access to legislative history documents from the 93rd Congress (1973) to the present. Because it's a free website, it isn't always as comprehensive as a resource like ProQuest Legislative Insight.
Additionally, Congress.gov will usually just have the documents most directly related to a bill. Broader policy documents, such as those produced by the Congressional Research Service, are unlikely to be available.
If you don't have access through ProQuest Legislative Insight through UA, and you are looking to create a legislative history for a bill from 1973-present, Congress.gov is a great resource.
To search Congress.gov from the homepage you can search:
Using the Advanced Search option (see screenshot below)
Clicking on a Congress.gov result will give you a summary of the status of the bill and an overview of it.
The easiest way to access the most relevant legislative history documents is to click on the "Actions" tab at the top of the page. This will lead to a timeline of the bill and will link to any available legislative history documents.
If the documents are not available for free online, there will only be a citation to the document, rather than a link.