Same issue. In some of X threads like this: https://x.com/antigravity/status/1990813606217236828 (comments section), they mentioned that they're working on resolving these overload issues.

Looks like a lot more people are trying to download this. Since they've released similar tools like Jules earlier, those were not really clubbed with major model releases like Gemini 3.0. This time they've clubbed the 2, so they seem to have received a lot more traffic than expected.

It should be fixed in a few hours when the traffic decreases.