Senators will have access to the classified documents, but only once a classification review of relevant materials has been completed. It is vital for national security that the intelligence community examines the records beforehand as the materials involve presidents, which complicates and lengthens the process of releasing the information to Congress. The intelligence community will ensure the classified information is not compromised and the country's security is protected.
The Biden administration is intentionally stonewalling senators from accessing sensitive material. The director of National Intelligence decides whether the senators can access classified documents. Since the director coordinates with the White House, it is unlikely the intelligence community can remain unpartisan if it answers to the person it's investigating. The administration should intervene if the White House and the intelligence community keep Congress from performing its constitutional duty.