If Construction Lines is running slowly even on a basic mesh, there is likely a conflict. Try disabling all other 3rd party add-ons to see if one of these is conflicting with Construction Lines. Having CUDA and OptiX at the same time can cause a viewport slowdown. Contact me through my website form if you are still having issues.

Mac OS and in particular Safari will often automatically unzip .zip files. Blender requires add-ons to be installed from a .zip so an unzipped folder won't work. You can disable auto-unzipping in Safari preferences, or use another browser. You can also zip the unzipped files and install the new .zip

Yes. Whether you pay for the beta version or any other version, you will be entitled to all future updates.