I haven't confirmed the exact wording on what passed, but the last draft I saw submitted was essentially requiring all documents related to UAP be release within 25 years of their creation. That would mean 1998 and prior would be due for release to the National Archives next year. Technically, the only exception would be anything the president deems shouldn't be released based on specific criteria.

However, without any review boards or subpoena power it falls on the groups holding the documents to be upfront with their release. The benefit there is that Congress should be able to pry out any cases they and the public are aware of. I wouldn't expect any details of covert operations, groups, or research to release without a fight. Though I would expect details of encounters, crashes, and recovered material be released.

And, while it won't be an official disclosure, the release of evidence would allow the public to come to disclosure on their own. That may not be a bad route. Once more people are aware of what the phenomenon entails then government officials can disclose to a tempered population.