I figured the problem out. The area I specified is still too big. However, I really hope plus code can allow people to download big area grid. I have already published a peer reviewed article and a technical article:
Wen X., L. Yang, Y. Zhang, Q. Wang, J. Ye, 2024. The temporal and spatial analysis of forest carbon storage using Google Plus Code: a case study. Carbon balance and management. 19 (13),
https://doi.org/10.1186/s13021-024-00258-0 (IF: 5.4)
Zhang Y., J. Stovall, D. Unger, I. Hung, D. Kulhavy, 2022, Plus Code: an Alphanumeric Code Geocoding Option for Professional Foresters, The Forestry Source, 27(2):1, 4.
What I mean is that plus code is a wonderful idea and it should be used more widely, not just position location.
Thanks.
Yanli