Welcome!
I don't know anything about this particular accelerator, but the mmu.library package requires Kickstart 2.04 or newer. I would guess that the IDE controller also requires a newer Kickstart - many accelerators with IDE ports mimic the native IDE port on the A600, the driver for which is contained only in Kickstart 2.05 and newer.
Which version of Kickstart 3 do you have coming? 3.X (note the capital X) is a custom release from Cloanto that roughly corresponds to OS3.9, but does have some bugs/compatibility problems on some systems. 3.1 is the traditional maximum version for the A500, but 3.1.4 and 3.2 have recently become available. If you're new to the Amiga, 3.2 is a good bet since it incorporates some important ease-of-use updates with regard to hard disk drivers and filesystems.
Two other new-to-Amiga notes if you weren't already aware:
1. Never, ever, ever plug or unplug *anything* from the system while it's powered on. Chips *will* fry.
2.
Aminet is the single most important software resource.