You should avoid "third-party" download sites (like those that pop up in ads) as they often inject malware into plugin zips. The only safe way to download an older version is from the official WordPress repository.
Many community-modified versions of 6.77 exist on platforms like GitHub that have already removed size restrictions. How to Increase File Size in 6.77 all in one wp migration 677 download top
Version 6.77’s free version cannot import files larger than 512MB. Workarounds: You should avoid "third-party" download sites (like those