I have solved this, in case anyone hits the same brick wall:
In the .pro file, the one selected in my screenshot, I needed to specify that it should install those aditional files.
In my case I mentioned that it should install the DISTFILES, like the following:
DISTFILES +=
weathericons-regular-webfont.ttf
Ubuntu-C.ttf
fontawesome.ttf
#set the path where to install distfiles aswell as adding which files to be added
dist_files.path = /Cumulus
dist_files.files += $${DISTFILES}
#you can see that at the the end I've mentioned that dist_files should be installed aswell
INSTALLS+=config_files qml_files desktop_file dist_files
Might seem dumb of me for not knowing, that the files should be manually set to install, but I haven't used it before since for Android Qt Creator does that for me because it has a special directory where I need to add the aditional files.
And on desktop I manually copied the files in the build directories without thinking I can tell qmake which files should also be deployed.
So in case any other has this issue might help them out.