WP_Query ordering numbers as letters

I have some meta_fields in user profile created with ACF plugin. I am trying to run a query to get users with the following criteria:

This is my query:

It runs OK, but i suspect that this query is treating numeric values as string values: for example, 9 > 100 or 2 > 18.

What am i doing wrong to make this order works in a numeric way?

Thanks.