Hey ttobles
Per the HQ first page's disclaimer:
Collabs are open to all Citizen members (membership is required to participate). You need to be subscribed by April 5th and remain subscribed through May 4. You're welcome to subscribe earlier so you can access the recommended courses listed below. This option could be helpful for focusing on learning from content before the collab begins at which point you can focus primarily on applying what you've learned.
and this is from the blog post about collab 2021 and collabs in the future:
The project officially begins Monday, April 5th. It's reserved for subscribing Citizen members. Again, you’re welcome to sub before April 5th to get a jump-start on the recommended content but if you want to participate make sure to sub by April 5th.
Register for COLLAB2021 by filling out this Form. Note that registering for the Collab is different from subscribing as a Citizen Member.
If you have questions don’t hesitate to ask in the comments below. You can also find more info at the HQ forum thread!
You might be able to do a trial membership for a period and sign up today, no?