As per the description above, the Adobe Send and Track is not sending over 1 page, Is that correct?
I have checked the records and found that the current Adobe Send and Track, Annual subscription has a billing issue and this could be the reason you are not able to send/use the services.
To know more about the subscription, please refer to the following KB doc Manage your Creative Cloud membership Link: https://helpx.adobe.com/in/creative-cloud/help/manage-cc-individual-membership.html
I have also sent the contact details of Adobe support via private message, please check your email inbox.
Hope this helps, and let us know how it goes.
As per our conversation in the private message, clearing/deleting few files from the Cloud storage fixed the issue.
As mentioned earlier in the message that you have an annual subscription to Adobe Send and Track, the cloud storage with your subscription is 2GB. You can check the same under your account on Adobe.com>Manage Account>Plans and Products or can refer to Creative Cloud file storage and quota Link: https://helpx.adobe.com/creative-cloud/kb/file-storage-quota.html
Hope this helps.