I am trying to install SourceTree on a computer running Windows10.
On the first screen of the Sourcetree setup wizard, I selected Bitbucket which starts an attempt to "Login to Bitbucket" but it never gets past this step. I am not prompted to login in any way. I also tried selecting the Bitbucket Server option -- just to make that wasn't the option to select -- and entered https://bitbucket.org as the root url and adamporad as the username. This didn't work either.
I confirmed that I have a Bitbucket Cloud account https://bitbucket.org/adamporad.
Based on some discussion pages I read, I verified that I am able to login to my.atlassian.com using IE11 and Edge and Chrome. One person said that he needed to add id.atlassian.com to the Trusted Sites list in IE, but the network admins have restricted access to updating the Trusted Sites but since I can browse to those websites I don't think it's needed.
I did consider that the network admins at my work have restricted some websites. I don't think that is an issue here since I can login to the atlassian.com and bitbucket.org websites. Although if there are other URLs the install is trying to access, I don't know about them.
This Atlassian Support KB article The installation, update or removal of SourceTree is not successul on Windows suggested trying the utility available from this Windows Support article Fix problems that block programs from being installed or removed.
After I downloaded and ran the utility, the Sourcetree install process worked correctly -- redirecting me to login -- and successfully finished the install.