Yes it's 2020 and as similarly reported here...
https://community.atlassian.com/t5/Sourcetree-questions/Install-Sourcetree-3-Windows-without-Bitbucket-Cloud-or/qaq-p/925281
and numerous times here...
https://community.atlassian.com/t5/Sourcetree-questions/Registration-Part-on-installation-stack-on-Registration/qaq-p/1275836
I'm unable to successfully install SourceTreeSetup-3.3.6...
Unwillingly I registered a Bitbucket account, linking it to my existing Jira account. When I run the installer, I click the bitbucket account. It displays a "Waiting for login to finish..." message and a indeterminate progress bar. A bitbucket page is launched in the browser asking me to grant a bunch of privileges to Sourcetree for Windows. I click the "Grant access" button. It transfers me to a localhost page which says "Authentication Successful... SourceTree has been successfully authenticated. You may now close this page." The installer removes the waiting message and the progress bar and returns me to the original step in the installation, with the Next button still grayed out. Leaving me no way to proceed with the install.
Clicking on the Bitbucket button again does nothing. If I click on the Bitbucket Server button then click back, then click the Bitbucket button again I can repeat the same failure all over again.
It's quite jaw dropping that a company like Jira could release such an obviously intrusive and yet totally non-functional installer for a product and still not fixed the issue over a year after receiving the first complaints about it.
My suggestion would be to remove the PUS (potentially unwanted service) from the SourceTree installer i.e. remove the requirement to have a bitbucket account
