Solution
The error “The link you followed has expired. Please try again.” when it occurs during theme upload, it is most likely due to a limitation on upload_max_filesize and post_max_size set by your web host. Please contact your web host to increase these 2 values to at least 32M. Alternatively you can use FTP to upload the theme.
Explanation
upload_max_filesize and post_max_size are PHP configurations that sets the maximum size of a file that can be uploaded. The theme file is 22MB in size and so if the upload limit is less than this number then you will get a link expired error.