Sign in to your TaxAct account online, click Orders and Downloads, click View next to your product, then click Download next to the state/return-type you want.
In the taskbar at the bottom of your computer screen, click in the field that says Type here to search, then type "file explorer", and click Open.
Double-click the Downloads folder, then Double-click the state file you downloaded (the file name is ta[last two digits of tax year][state abbreviation][form number].exe. Example for 2021 Alabama Form 1040: ta21al1040.exe).
On the screen titled Do you want to allow this app to make changes to your device?, click Yes.
Follow the instructions provided on your screen to complete installation.
Update a return to add a State:
After installing a state, from within your TaxAct return (Desktop or Professional), click Return in the upper menu bar, hover your mouse over State, then click Add/Remove State...
In the window that appears, click the Checkbox next to the state you want to add, then click OK (clicking the checkbox will select or deselect the box, make sure the state you want to add is selected).