I apologize for this experience you've had uploading your PDF! I took a peek at your account and can see you were able to upload two separate PDFs into your library. Are you still unable to upload your PDF? If so, are you receiving any error messages? Have you tested uploading in a different browser or a private/incognito window? Please let us know these details so we can troubleshoot further.
After several attempts at uploading using Firefox, I tried using MS Edge and was able to upload. However, I couldn't use Edge to edit my email, and had to switch back to Firefox.
We're sorry for any troubles and glad to hear you were ultimately able to get your file uploaded to the Library. Sometimes trying another web browser that is compatible with Constant Contact helps! Especially if there's possibly a third party add-on preventing a specific action in your account. What type of file were you trying to upload? Was there an error message? Knowing a bit more about what happened will help us troubleshoot for you so this doesn't happen again!