It looks like for 5th ED you would need
Standard Licence
and as a player
Core Pack Which includes the inbuilt players manual for making characters as well as
Core Monster Pack as a DM
Then you can tack on any of the Adventures as you go along I guess as a DM Like
Curse of Strahd
I'm assuming that only the DM needs the adventure packs?
It looks like it has some 3.5ED Adventure packs, but the Core Packs are 5E it appears.
Edit: Thinking about it, might need the Core player pack and the Monster pack as a DM, as core player pack might help for making NPCs?
Edit 2: Argh, Just found the
DM Guide too, lol, Expensive old stuff.
Edit 3: The Fantasy Grounds D&D Complete Bundle seems to include all of the above plus some more adventure packs. However it's expensive at £243.. (All 5th Ed)
I've not played any D&D since the late 90s I'm pretty sure I played mostly 2nd - 3rd Edition.
Dragonlance, DarkSun, Forgotten Realms (Inc Al-Quadim) and some Ravenloft..
Brilliant fun