In case you registered for a trial account on Intuit's commercial tax product site for tax professionals, you are in the wrong place and must pay for each return you print (or e-file), although you may prepare and view a return on the screen without charge.

If you are a student taking a tax course at an accredited academic institution, you should register for an account on the Intuit Education website, which is run under a different program that is not supported by the commercial product teams who frequent this peer-to-peer forum.  Intuit Education's URL is https://www.intuit.com/partners/education-program/registration/students/proconnect/.

The commercial version of ProConnect Tax Online for 2018 was released last month but I am not sure whether that has been rolled out for trial accounts and under the Intuit Education program.

In the event you are not a student at an accredited academic institution but are studying for VITA, this is not the right place either.  You should refer to https://apps.irs.gov/app/vita/ for more information about the resources available to you.  I believe TaxSlayer Pro has a practice lab that you may access once you sign up for an account with the IRS.

Whichever tax software you use, it is expected that these early releases will not be fully functional or accurate, especially due to the large amount of changes related to TCJA and the impending release of regulations/guidance from the Department of Treasury and the IRS.