Allright, I had an email exchange with Richard on how to install all the files on the drives. I'll try to copy what is relevant here.
1. you need to install Arduino IDE
2. Install the following 2 plugins: 1. arduino-esp8266.readthedocs.io/en/latest/installing.html

2. github.com/earlephilhower/arduino-esp8266littlefs-plugin


3 in Arduino . Select board: see screenshot 1
4.Ensure board options are as follows (particularly the Flash Size must be FS: 3MB): see screenshot 2
5.Create a new empty project - call it something like 'test'. Once the new project is created, open your file manager, and create a new empty folder called 'data' in the folder containing your test.ino file.
The folder/file structure should be as follows: see screenshot 3
6.Copy the mounts files (from the Astrotrac website) to the data folder you've just created.

7. Power up your 360 drive, connect to it's WiFi access point.

8.In the Arduino IDE, you should see your 360 drive's IP address on the port menu, under the COM ports IP address not shown in the below screenshot):see screenshot 4
I did not see the mounts adress here right away, but got it afer restarting my computer while still connected to the drive's wifi. That worked
9.
Goto the Tools menu and select the ESP8266 LittleFS Data Upload option - this will upload everything you've placed in your sketch 'data' folder (the mount.js.gz file) to your 360 drive:see screenshot 5
Only takes a little while to copy all the files, after that things should work again.