Hi Migsun,
If you stick this in your wp-config.php, then it will then allow you to go lower than 100Mb in the settings:
define('UPDRAFTPLUS_SPLIT_MIN', 1);
However, if your limit is 10Mb then you may be fighting a losing battle. It sounds like time to find a new web hosting company! I actually never came across a web hosting company with a limit less than 2048Mb before...
David