Nube: 1st-time Installation Storage Settings; How to set or troubleshoot?

[apparatus]

If you want to dedicate the entire PC hard drive to install Qubes OS then you need to remove all other partitions on the drive and use automatic partitioning like this:

Troubles with installing QubesOS (not enough memory it claims)

Select Custom, press Done button, then on Manual partitioning screen remove all partitions with - button then press Click here to create them automatically for installer to create default partitions. You can find more info and images here: