Bootcamp asking for more space, but Mac has the space needed

Hi,

I am trying to run Bootcamp to install Windows on my Macbook Air 2015. Once Bootcamp has been executed after clicking on "Continue" on the first screen I am facing an error message informing me that the machine doesn't have space available, space needed: 42GB. Checking storage info I have 94GB of free space.

I've tried:

* Uncheck automatic updates;

* Unsync with iCloud Photos;

* Removed everything possible;

Update macOS version isn't possible because newer macOS versions aren't compatible with my machine.

More information is in screenshots.

Thanks.

[Image Edited by Moderator to Remove Personal Information]