I downloaded Arc Pro and made an Esri account but it will not let me sign in because I don't belong to an organization and my account is public. Is there a way around this? or any organization I can join? I just want to practice using ArcGIS.

[MarkMilan]

I have the Esri Press textbook 'Getting to know ArcGIS' and on the back cover it says there is a free 180 day trial to do the examples in the textbook.

[curtvprice]

Getting To Know ArcGIS is for ArcMap, not Pro. 

I suggest looking at the ArcGIS for Personal Use Program