1. The engine: Daggerfall Unity releases
2. The game data file, often called DaggerfallGameFiles.zip: official copy in google drive

1. Create the directory you want the game in (e.g., ~/games/dfu)
2. Unpack the engine in it
3. Create an empty file called Portable.txt (i.e., touch Portable.txt)
4. Unpack DaggerfallGameFiles.zip in a temporary directory, and move the resulting arena2 in the game's directory DaggerfallUnity_Data/StreamingAssets/GameFiles
5. Delete the temp directory

1. Start the executable (e.g., DaggerfallUnity.x86_64)
2. Pass the settings, there are several values that you may want to change; here are few ones:
   1. Swap Health & Fatigue
   2. Advances, Enhancements, Instant Repair Service
   3. Advances, Enhancements, Enable Game Console

1. Create a script to ensure to have the TERM env variable set to dumb

#!/bin/bash
cd ~/games/daggerfall-unity/engine
TERM=dumb exec ./DaggerfallUnity.x86_64 "$@"

Without it several mods will fail to work because of a Mono bug and the log will be littered of errors like:

[Error] [name of the mod] <b>Compilation Error </b>: The type initializer for 'System.Console' threw an exception.
	at line#0 column#0 

The Champion Classes mod has good starting classes and in the bottom of the page a list of suggested mods.

Download the mods in different directories (one per section is fine) and in each directory you can create a tmp directory and from it execute 7z x .. and with a bit of luck the resulting data can copied in DaggerfallUnity_Data/StreamingAssets . Of course double check before copying.