Forms mode is a feature of desktop (CD/download) software only. With online TurboTax you do not have direct access to the forms until you have paid all your fees. Until then you can only preview your Form 1040.
PREVIEW 1040
https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing
Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.