First check out that you are starting the Qt Creator version with the Ubuntu SDK plugins enabled.
If that does not solve it for you, you might be running into a known issue: it seems the Qt 5 runtime is not automatically detected by Qt Creator.
If you're affected by this, you will need to tell Qt Creator where the
qmake binary file is in order for it to present you with the template wizards.
Fortunately, that's really straightforward:
Start Qt Creator (type
ubuntu sdk on the Dash)
Go to Tools → Options
Select the Build & Run section
Select the Qt Versions tab
Click on the Add... button
In the file picker that just appeared navigate to the
/usr/bin folder and select the
qmake file (it might take awhile to appear), select it, and click on the Open button. If this doesn't load also try the
qmake file located in the
Click on the OK button. The Qt Versions dialog should now look as the picture below
You should now be all set. Try the Ctrl + N shortcut (or go to File → New File or Project...) to start the new project wizard. The templates should now be in there.