How do I install the 1.5 branch that has many fixes?

Hi, I love this addon, but half of the features seem to barely work for me. I wanted to install the 1.5 branch to see if it would be better, but I get this error when trying to install it with the .zip file. How do I install it? Any help is appreciated, thanks.

<img width="808" height="311" alt="Image" src="https://github.com/user-attachments/assets/4f73d652-e1ca-41f3-8868-de33885a9c35" />

