LADSPA - could not load .so files


I use a 10.13.6. High Sierra Mac OS and Audacity 3.1.3. The older Audacity version (2.0.2.) had no problem using the LADSPA plug-in. The data are in the correct folder \Library\Audio\Plug-Ins\LADSPA, but still it says after activating “could not find file” and shows the exact path where I put the files to. Any ideas what seems to be the problem?

Thank you.

The LADSPA plug-ins for macOS are ancient 32-bit plug-ins. They are too old to run on a modern 64-bit Mac.