We are often asked why the zip file is named as it is named. There is a reason. Here is the explanation:
avastar-M-m-rrrr_blender-B-bb.zip
-
avastar: the product name
-
M: The major product release
-
m: The minor product release
-
rrrr: The product revision number
- B-bb: The earliest version of blender supported by this particular Add-on version
Usually you are safe to download the zip file with the highest available product revision number.
Only if you encounter a bug in Avastar you should consider to switch back to an older Avastar release by installing that over your current release. There is no need to uninstall first!