Thanks. I can't see anything wrong there. Try installing the update again -
To install the update to ZAppLink:
1. In the ZBrush 4R5\ZStartup\ZPlugs folder, delete the
ZAppLink_4.0.zsc (circled red in the attached image). Don't touch anything else.
2. Download the
ZAppLink 4R5 update here and save to your Desktop.
3. Unzip the file, open the containing folder created by the unzipping and locate the
ZAppLink_4.0.zsc file.
4. Copy the
ZAppLink_4.0.zsc file to the ZBrush 4R5\ZStartup\ZPlugs folder.
5. Restart ZBrush.