The First Aid tab is grayed out and I am not able to click on it. What is my next step?

Make an external backup or two, wipe the storage HDD or SSD, and reinstall from Apple macOS and Server.app distributions and migrate in your data as part of the installation.

If there are additional user-created partitions on this storage device, back up all partitions.

Time Machine to an external storage device or a disk image to an external storage device created using Disk Utility, or both.

Erasing your storage is the end of all data on the device, so having a backup or two before that step is very important for any future access to that data.

It's possible that whatever happened here is a software corruption, but it's also distinctly possible that the underlying storage is failing and in need of replacement. Systems running Lion or Lion Server are fairly old hardware.

If this is involving Server.app and running something as old as Lion Server, then the recovery can be a little more involved, depending on what else has gotten corrupted. An import into a fresh install of Lion Server will usually pick up the old data. Whether that data is uncorrupted?

If the storage hardware is failing, then even the I/O load from the backups can cause additional data corruptions or can potentially degenerate into complete storage failure. Which means having a current backup now is important.