Yes - you need to take out the rails to make it fit. The rails are fixed with 4 torx screws per rail, each one with thread lock. It is a good idea to re-apply thread lock when refitting as these rails are all that holds the seats to the car so you really don't want them to work loose.
Really interested in how you have tackled the tie downs. If you are able to explain once they are done that would be great!
Lots of Citroens and then a Peugeot