prior to answer please tell us the level of the class and what a kind of dye is wished for this e.g. these simulation (s) and infos about your O.S. e.g. Windows 10 or Mac or Linux.
A: I read all. In the case of The sim4t I was unable to use it because I need to have a login apparently. The student version apparently does not work.
The Simulation of U.V.-Vis. Photometer also I was unable to use it
The fluortools aplication is a software to analyse data. Apparently the application don't simulate spectra.