Can I purchase paid access when I’ve already collected all the free rewards?

If you have already collected all the free rewards in Seasonal Rewards mode, you can still purchase the Pass and get all the paid rewards that were previously unavailable to you. You do not need tokens to collect them. All rewards can be collected immediately after you purchase the Pass.
Please note that there is a time limit on Pass purchases, so be sure to buy the Pass before the timer runs out. The timer runs out on the last day of the current season.