It looks like there is some kind of issue when it comes to routing as the required assets aren't being loaded correctly.
What type of webserver are you using?
Regarding PHP Safe Mode: that doesn't actually exist anymore. It was removed from PHP in version 5.4.0. This check is no longer part of the preview builds of FOSSBilling and will be gone in the next release to reflect that.
If you want, you can review the system requirements although it's rather unlikely the issue you are seeing is a result of a requirement not being met.