After playing the game for awhile longer, an advisor bubble came up that allowed me to open the settings menu and finally log in to my city ^^
Thank you!!! I played 'til about level 4 and then Eva the advisor had a pop up advising me to save my game to avoid losing my progress. Tapping that bubble took me to the settings where I could log in to my old city. To get the bubble to pop up, try making sure all apps are exited, then turn on airplane mode, then open simcity builidit and visit Daniel's city, then return to your city and Eva might pop up with a bubble advising you to save your progress (otherwise I think if you keep playing for awhile without internet access it might pop up). Tap on the bubble and settings will open. Turn off airplane mode to regain internet access, and then you can do whatever you wish to do in settings. 🙂
