After the changes have been applied, click GParted > Quit to return to the main installation window.
Back to the main installation window, you will have to click on the Refresh button to see the partitions you created with GParted. Afterwards, double click on each partition to set the mount points.
Here you have to set the mount point and file system type for the partition. You will have to repeat this step for all partitions before proceeding to the next phase of the installation process.
When all the mount points have been set, click Forward to continue with the installation.
By default, the installer will install GRUB, the bootloader, on the Master Boot Record (MBR) of the hard disk. You may opt to install it on the boot partition, but it is best to stick with the default location. Click Forward to continue with the rest of the installation.
That should do it. When the installation completes, you should have a machine powered by a Linux Mint edition with rolling updates.