Hi,
Here’s a link to the [https://topics-cdn.dell.com/pdf/inspiron-15-7568-laptop_service-manual_en-us.pdf|service manual] for the laptop, taken from this [https://www.dell.com/support/home/us/en/19/product-support/product/inspiron-15-7568-laptop/docs|webpage].
Scroll to p.17 to view the necessary pre-requisite steps and then the procedure to remove/replace the memory module.
According to the [https://downloads.dell.com/manuals/all-products/esuprt_laptop/esuprt_inspiron_laptop/inspiron-15-7568-laptop_reference%20guide_en-us.pdf|specifications] (taken from the same webpage as above), the laptop supports DDR3L 1600 MHz 4 GB and 8 GB RAM but I won’t argue with what is stated by Crucial in the link supplied in the answer above