Hello,
Thank you for posting in the community!
You are part of an Enterprise account and listed as a Limited-access user. You will need to request a license to make edits/create diagrams. If you would like edit access, please request a license via the popup in your original message. You can also open a document and click on the orange banner at the top of your document.
Licenses are managed by the admins on your account. We would recommend reaching out to your internal IT for further help on your license request.
Thank you for your time and please let us know if you have any other questions.