1. first you need to create your custom vsnd and vsndevts files according to the guide, and make sure your sounds work in game (tools mode)

2. create such directory structure: Half-Life Alyx\game\hlvr_addons\<your_addon_name>\scripts\vscripts

KEEP IN MIND: it's **game\hlvr_addons** not content\hlvr_addons

3. enter the vscripts, create a file with name "precache.lua" (or whatever name you want, but with ".lua" suffix)

4. open the file, enter such code (exclude the equal sign lines):

=============
function Precache(context)
    PrecacheResource("soundfile", "soundevents/<your_soundevents_file>.vsndevts", context)
end
=============

if you have more than one event files, use more PrecacheResource lines

vsnd files don't need to be preached

5. open hammer, choose an entity that will spawn at map start (for example a logic_auto)

6. change its "Entity Scripts" property (under "Misc") to "precache.lua" (or the name you selected in step 3)

7. compile map, upload to workshop, test your published version