Hi marcodegama93
Go to the
Object Manger> Tags> Render Tags> Compositing Tag
while your object is selected, it will be applied to the object that should not cast a shadow.
Now the Tag itself needs to be selected. Go to
Attribute Manager> Tag> Cast Shadow: un check.
BTW, this will not change Global Illumination.
https://help.maxon.net/c4d/s26/en-us/Default.htm#html/TCOMPOSITING-ID_TAGPROPERTIES.html#COMPOSITINGTAG_CASTSHADOW
All the best