Check and see if the Captain Sim aircraft is in the new installation location: X:\MSFS\Community\captainsim-aircraft-m### (### being the product name - m131, m764, m772, m773, or m774).

If it's not there: Login to Your Profile > Product Name > Extended Download Service. Download it/them from the link(s).

If you didn't uninstall it from your computer before moving MSFS to the different drive, and it didn't copy over, then its likely that you will need to get the order number unlocked. The guide to do that is here: https://www.captainsim.org/forum/csf.pl?num=1541289733