If she has been using Amtico products from new then carry on but if not you can use a compatable product but ask your local suppliers first.If in doubt use Amtico only.
To strip and clean Amtico flooring you'll need to sweep the floor first.
Apply dressing remover, roto with a blue pad, wet extract floor allow to dry and apply 2-3 coats of dressing using terry towels made into a pad ( canes the knees) or use a new/very clean mop allowing 1/2 hour between coats.
Amtico license their cleaners and fitters and Amtico will only honour their warranty if the customer has used a licensed cleaner that has followed their procedure for cleaning.In other words if you scratch the surface or damage it in any way, then the floor will become yours and you will have to supply the customer with a new one
Thats not to say that if confident you can not maintain it as after a bit of practice it's very simple and profitable to do.
For maintanace clean with Amtico floor cleaner in the usual way.
Good Luck