Windows cannot be Install in this drive
. just click the 250 GB volume and Delete Volume then click New Partition Name it and click Next to install windows. Now, once you've successfully installed windows on your machine, then just reboot & process to next step installing Linux (if you like to triple boot) otherwise skip Installing Linux and proceed to Final Step below!!Linux Swap
and Volume Type as Logical Partition then give volume size 2 GB. then again click on Free space and click on (+) and select partition type as Ext4 File System
and select type as Primary Partition. (48 GB in my case because 2 GB is used for SWAP Partition above). Now, click on Install Now and wait for installation finishes. Once completed reboot. Please read detail guide on installing Ubuntu 18.04 hereby @ALiveVam