The README.cmake says :

For debian/ubuntu user the following command will check for
required packages to build KMyMoney:

sudo apt-get build-dep kmymoney

When I run that i get:

Reading package lists... Done
E: You must put some 'source' URIs in your sources.list

I cannot find what "source URIs" I need to add and searching forum was no help. I am assuming that source URIs means other repositories but which one(s)?