The Ubuntu 16 LTS build instructions you provided don't work from a fresh install, even after an update/upgrade. Also, the tar you provided won't run 2ACoind. "Illegal instruction (core dumped)."
The 2ACoin.exe found within the Windows zip file is returning, repeatedly:
2018-Aug-01 23:20:04.457837 INFO [94.244.156.69:52113 INC] Your 2ACoin node is syncing with the network. You are 1246 blocks (1 days) behind the Network. Please be patient!
2018-Aug-01 23:20:04.887497 ERROR [94.244.156.69:52113 INC] Failed to handle NOTIFY_REQUEST_CHAIN. block_ids doesn't end with genesis block ID
Try them all using your instructions and you'll see what I mean.
What, if anything, works in order to mine this coin?
Okay, we have a solution for you dealing with the Windows version.... If you were running a previous windows version then you will see this issue;

The problem is that you have an OLD BLOCKCHAIN from our TEST version in the following location;
C:\Users\YourUser\AppData\Roaming/2ACoin/DB
To Correct this:
- Delete the folder C:\Users\YourUser\AppData\Roaming/2ACoin/
- Restart 2ACoind and allow it to sync with the network
You should start seeing the syncing messages once 2ACoind is restarted;

If you need additional assistance visit our support channel at
https://chat.2acoin.org