To play effectively the most important thing will be good communication. An audio chat client like Discord is a great pick because of their great quality audio and tools in chat. Consider using Discord's "Priority Speaker" setting in voice channels to let the DM's voice take priority!

You'll also want to be able to create characters and share character sheets, Tableplop has support for character sheets in campaigns and there are other great options like dndbeyond that support certain roleplaying games officially with character creation and official content.

Lastly you can use Tableplop to visualize encounters!