You have until the end of January to download your purchases. I assume it's okay to link to the official post, since it sounds like Renderosity is involved in the transition.

https://community.hivewire3d.com/threads/hivewire-3d-store-officially-closing.4333/#post-203060

We are making arrangements for customers to have till the end of January 2021 to be able to download all content they have purchased, even though the actual store will close on January 4th.