DOC: Add instructions for macOS

README_SETUP.md

@@ -19,6 +19,22 @@ julia> using CaosDB
 julia> connection = CaosDB.Connection.connect() # Enter host, port, path to SSL certificate, and credentials here
 ```
 
+### Troubleshooting
+
+On MacOS, if you encounter errors like
+
+```
+could not load library "libccaosdb"
+dlopen(libccaosdb.dylib, 1): Library not loaded: libcaosdb.dylib
+  Referenced from ~/.local/lib/libccaosdb.dylib
+  Reason: image not found
+```
+
+(note that the library that couldn't be loaded is `libcaosdb`, i.e.,
+the wrapped cpp library couldn't be loaded from the c interface) make
+sure you have the location of `libcaosdb.dylib` and `libccaosdb.dylib`
+in both, your `LD_LIBRARY_PATH` and your `DYLD_LIBRARY_PATH`.
+
 ## Tests
 
 After installing, the unit tests can be executed by