Welcome to OpenMandriva!
The welcome app should have had a pop-up asking for your password, but I don’t know why it wouldn’t work for you.
Your Linux experience will be much better if you learn just four terminal commands.
dnf search name
sudo dnf install name
sudo dnf remove name
sudo dnf dsync
Replace ‘name’ with an actual name or keyword to search for, install, or remove software that we have in our repositories. The dsync command will update everything on your system.
Any trouble you run into, or if you have any questions, we’ll try our best to help.