My workers have iphones with ios12, but i have a problem downloading the compatible version.

My workers have iphones with ios12, but i have a problem downloading the compatible version.

Hello, I have the ios12 version on my workers iphone. When I download Cliq from the AppStore, it says that the new version is not compatible but will download a previous version, so it will be compatible. The problem is that when I open the Cliq app, and login I’m not able to enter the app, it closes immediately. Can you help me please. 
Because of the iphone model is not possible to upgrade to ios13.
Many thanks for your help in finding a solution.