One problem is that Bower is now considered a deprecated tool and Yarn is a new replacement. So if you've just installed Bower then it's very likely that you visit this page because you saw the following warning message pops up after install Bower:
npm WARN deprecated firstname.lastname@example.org: ...psst! Your project can stop working at any moment because its dependencies can change. Prevent this by migrating to Yarn: https://bower.io/blog/2017/how-to-migrate-away-from-bower/
This is not an error, this is a warning message
The message above does NOT mean that the system has encountered an error during the installation process. Instead if there's no other error message and it means Bower has been installed successfully and you can use it right afterward. Check its version by running the following command on terminal:
$ bower -v
The reason why we see this warning message is because Bower is obsolete and should be used mainly for maintenance purpose. You can still use Bower for old projects but for new one you should consider using other tool. The author recommend us to use Yarn.