Please kindly check the following values in your PHP info.
You can use this plugin https://wordpress.org/plugins/wordpress-php-info/
Most likely your post_max_size and upload_max_file_size is lower than Evolve+ and Alora Theme files size.
Both themes are 12.8 Megabytes and 11 Megabytes. Your hosting server will reject the theme zip file if it exceeds the limits. WordPress shows you this not helpful “all purpose” error message when it catches something wrong.
You may need to increase the max_execution_time because it takes more time to unzip a large file, this depends on web server processing power, so I cannot give you a specify value.
You may want to contact your web hosting company for assistance in increasing these limits.
Alternatively you can unzip the theme file on your computer and upload to your web server’s WordPress installation via ftp.
This is quite common situation with using any premium themes on a shared web hosting, which has limited shared resources.
You will have no problem uploading Evolve (Free Theme) because it’s only 4.3 Megabytes.