The Starter Edition includes the following:
Full access to the game’s Operators, Maps, Modes, weapons, and attachments Full progression (level cap) Same servers as Standard and Gold Edition 2 Randomly unlocked Operators (chosen from a pool of the original 6) 600 R6 Credits that can be spent on an additional 2 Operators or additional content
The catch comes at the hand of a fairly steep grind to unlock remaining Operators. Ubisoft estimates that unlocking a new Operator in the Starter Edition will take approximately 15 hours; where comparatively it would take 0.5-2 hours with the Standard Edition.
The Starter Edition can be upgraded to the Standard or Gold Editions at any time, and is also compatible with the Season Pass offered. This is a time sensitive offer that only lasts until June 19, and is only available on PC.