They are incremental updates which must be installed on top of the current official MusicBee release. Usually they are .exe files which will self-install, but if not you can use the instructions below.
Steven also provides frequent (often daily) patches with small tweaks and fixes. These are usually linked from MusicBee Forum threads in which issues have been addressed. The link remains the same for a while, and Steven simply updates the files.
Like the betas, these are more likely to solve problems than introduce them, although there is a higher chance of a serious bug being introduced as new features are added. To install one, close MusicBee, copy all items in the .zip file to your MusicBee installation folder, replacing any existing files with the same name (if you have a standard installation, you will probably need to grant administrator permission), and restart MusicBee. It is recommended to always install the latest patch before reporting a bug, in case it has been fixed already.
The latest 3.5 patch is available here.
- Official Disclaimer: As with any beta software, you install at your own risk.