In the past players have been able to find the tutorial quest at the siege range and then been able to pick it up and finish it from there:

https://forums.elderscrollsonline.com/en/discussion/435314/not-able-to-get-cyrodill-quests-dailies-anyone-else-had-this-problem

https://forums.elderscrollsonline.com/en/discussion/403309/no-starter-quest-welcome-to-cyrodiil-after-abandoning-it

Might be worth a look. It seems to occur if the training quest is abandoned partway through.