However, after issuing the command 

./GetComponents --parallel https://bitbucket.org/einsteintoolkit/manifest/raw/ET_2019_03/einsteintoolkit.th

I received the response 

"You have requested a subversion checkout, but the system was unable to find subversion.
Please enter the path to subversion: "

Not sure how to respond. Can you please redirect me about what to do here? ( the previous two commands given in the page worked fine). 

Thanks , 

Arshad Momen