Starting out a Dungeon Synth project is an exciting endeavour. I have collected some resources that should help newcomers getting started with making music. No guide can ever be comprehensive, but these are great starting points.
Awren's Dungeon Synth primer is my to-go recommendation for someone who wants to get their bearing into this music-making quest. It has some suggested listenings, a list of common gear (both software and hardware) and some ideas on composition. A spinoff of Awren's primer is the /r/DungeonSynth neocities page: it expands on some sections such as the history on DS, and also has a very interesting section on album art (recommendation number 1: don't use AI art! There are so many reasonable alternatives out there).
Mogwarn/Subterranean Dungeon Free Dungeon Synth Resources, despite what the name suggests, is a quite in-depth discussion on starting a dungeon stynth from the initial concept onwards. There is a lot of helpful talk on gear, but also on production (mixing, mastering, how lo-fi you want to get), distribution, art, worldbuilding, inspiration... You don't have to read everything in one sitting, but it's a good idea to check out the parts that are most relevant for your current place in your music journey. Then bookmark the page and come back to it as your needs change.
The pages I linked above have terrific recommendations for starting VSTs and gear. For further gear recommendations you might also want to check out this Reddit thread.