"Get it free/purchase button not working"

Sorry to hear it. Please try holding the power button on the console for 10 seconds until it shuts down to see if that solves the issue.

the video.xbox.com solution worked for me, clicked on season 1, then the purchase button said free.

It finally worked when I went to the online store and purchased Episode 1, even though it came with the season pass. It was free to click the purchase button, but that must have triggered something. Then, I was able to get Episode 2.

For now, looks like I can only get one episode at a time. Thank you for your help.

If you didn't get to click the "Get" button at any point, this also applies if the game just doesn't say you own it, then you can't get it. That's how Games with Gold works, games are only available through a certain period of time. When they're free, you've
gotta click the "Get" button in place of the buy button to get it added to your gold account... if you miss the window of opportunity you'll have to buy it. However, it sounds like you managed to purchase if you got a download going. So, make sure to check
your "Ready to Install" games or the "Gold" section on that same page.

If not, you'll have to buy it. In the future, you can purchase games that are free with Gold and add them to your account online on Xbox.com.

Same here. Happens at least once a week where I have to keep clicking and eventually it will start the ad. Today, I can't get it to start no matter how many times I click it. So frustrating.