#notes from https://www.cyberciti.biz/faq/increase-file-upload-size-limit-in-php-apache-app/
Increase file upload size limit in PHP-Apache

Type the following command to edit the php.ini:
$ sudo vim /etc/php/7.0/apache2/php.ini

Find and set the following two values:
post_max_size = 100M
upload_max_filesize = 100M

Save and close the file. Where,

post_max_size = 100M :
upload_max_filesize = 100M : Maximum allowed size for uploaded files.
Restart Apache server

Type the following command to restart the Apache2 server:
$ sudo service apache2 restart

OR
$ systemctl restart apache2.service

Now you should able to upload file upto 100MB: