Activating CiviCRM in Wordpress returns a fatal error, this is on windows10, all works until activation
My assumption is that you are using PHP 7.4. Dat version does not support curly braces syntax. See this answer on stackexchange https://stackoverflow.com/questions/59158548/array-and-string-offset-access-syntax-with-curly-braces-is-deprecated . A downgrade to PHP 7.3 will help. That is also the highest supported version, see https://docs.civicrm.org/installation/en/latest/general/requirements/ .
Another option is to fix the issue and create a patch for it. A remark on the https://lab.civicrm.org/dev/core/-/issues/1496 will also help.