That's too bad.
It is usually possible to continue using Quicken without renewing the subscription, but you will have to suffer the intrusive ad reminding you to renew, that occupies a significant portion of your screen. Too bad, since renewing rarely brings anything new, and merely continues features that many users don't want or use. Every time someone figures out how to make the ad nag disappear, Quicken alters their software to prevent the fix.

Your other issue, the "You have exceeded the maximum number of datasets. You cannot create a new dataset....." appears to be related to using Quicken's Backup/Restore command. Using Copy/Paste to save a backup copy of your data file and, if needed, restore that backup copy, instead of using Quicken's Restore command, reportedly prevents this message from reappearing.

Since Quicken was sold by Intuit (to HIG Capital in 2016, who sold it to Aquiline Capital Partners in 2021), the program and its customer service have become less of a user-friendly product owned by a software company, and more of a money-making enterprise owned by an investment company.