oF has a script for templates for Qt Creator in /scripts/qtcreator/install_templates.sh.
Then, to import or create a new project with Qt Creator, select File → New File or Project, and select openFrameworks as the “Projects” type. oF projects like the emptyExample or any of the examples need to be imported the first time you build and run them. This lets Qt Creator set up its own file(s) for building and running the project. After that, the project can be opened with File → Open File or Project. The templates also set up a new project kind of like the project generator, so you’ll have a chance to select folder location, addons, git, etc for a new project.
Also, I run the compileOF.sh script as sudo, which might be the only way to do it. Sometimes I need to recompile oF after updating the operating system (Mint 19 in my case).
Hope this helps.