Hi Paula,
after looking for a solution for install the last version of OpenCobol, I have found this link that explain how install the last version of IDE from source.
https://consulting-bolte.de/index.php/tech-blog/cobol/184-install-cobol-on-macos-x
Follow the instructions and run the program from command line, it works fine with my macOS version (10.14.6 Mojave)
Gaetano.