Unable to Install Ubuntu MATE 15.04 Desktop 64-Bit

[wolfman]

All I can really suggest is you read this, it does try to explain about partition sizes:

GParted partition guide for Linux and Windows users

PLEASE NOTE: THIS GUIDE DOES NOT DEPICT THE INSTALLATION (CREATION) OF A UEFI PARTITION. IF YOU HAVE A COMPUTER WITH UEFI/BIOS, MAKE SURE YOU ALSO CREATE A UEFI/BIOS PARTITION AS WELL. SEE FURTHER REMARKS ABOUT UEFI PARTITIONS IN THE GUIDE!. Linux beginners should also look here: You can only partition on an unmounted drive using an installation disk of your Linux flavour with a partitioning tool included, use the Gparted tool in live mode, or you can download a copy of Gparted from the link…