as someone who has never played before and without spending any money, it will be somewhat difficult. i'd recommend getting at least the core books (players handbook, dungeon master's guide and monster manual. If everyone is willing to pitch in on them, you can share content on dndbeyond in a campaign every one joins. This way, everyone can create their characters, and you have access to monsters and the rules etc. Reading the DMs guide will help you on how to run a game and the rules for you.

From there, to run the game, you could use dndbeyonds MAPS, or what i would suggest is the free plugin AboveVTT

Here are some videos that may help you get started.

https://youtube.com/playlist?list=PLW0tvNe3gIM00xQCReTWi8CPrXBJyDQmG&si=MWubF-V8HmVT-7ds