With Pix4Dmapper Discovery, there is no time or image limitations. The only limitation is the processing possibilities and resulting outputs. Basically, it is only possible to obtain a quality report and produce 3D video animations from the rayCloud scene.
In other words, you cannot run step 3.
For more information about the possibilities of the Discovery version compared to the Pro (full version), please see:
When you feel ready to generate outputs, you can ask for a 14-day trial and have full access to the Pro version of the software for free.
During this period, you can use the software as many times as you want without limitation: https://support.pix4d.com/hc/en-us/articles/202560729