Are you trying to to a new computer, or are you having trouble activating a student version ? I can give you specific steps for either. Activation and licenses | Adobe Substance 3D Painter
To obtain a Substance Painter license file, follow these steps: substance painter license file
C:\Users\Username\AppData\Roaming\Allegorithmic\Substance Painter\license.key (or under the Adobe folder for newer versions). Are you trying to to a new computer,