Hello SeaHuntress,
Welcome to the Microsoft Community.
I understand the inconvenience of not being able to access the content library feature. I've checked both Clipchamp for Windows and Clipchamp for web in the Edge browser and the Content Library tab is visible and does not require any paid subscription.
First, make sure you have the latest version of the Clipchamp app installed. This can be done by opening the Microsoft Store and then searching for Clipchamp and checking for updates.

I suspect it's due to not being on the right page, when you visit Clipchamp Online directly through your browser and click on New Video, is the “Content Library” feature visible correctly?

Please refer to New! Content library tab in Clipchamp | Clipchamp Blog
Looking forward to your reply.
Best regards,
Ian - MSFT | Microsoft Community Support Specialist