WILL YOUR PRODUCT WORK IN MY GARMIN 741XS
There really is no "product" here. GPSFileDepot is a collection of free maps by many different authors. They use the standard Garmin map format that is primarily intended for outdoor/handheld GPS units, however they work to some degree on Garmin automotive devices. They also generally work on older Garmin Marine devices.
However, according to this thread, they are not likely to be compatible with newer Garmin Marine units. https://forums.gpsfiledepot.com/index.php?topic=4337.0
They will probably just be ignored if you try loading them. But since I don't have a Marine Device, I can't say for sure.