What do I need to run floppy

If you are okay with 3.5” floppies and can find the appropriate disks (400/800k for Unidisk and 720k/1.44MB for the MFM SuperDrive. This tends to be the better option since t’s backwards compatible with 400/800k disks, and formatting. However, while you can find the drives the 720/800k floppies tend to be less common. You can read more about the drives you can get here as well. It will generally cost more to do it this way, so keep that in mind if you decide to get this drive setup for the machine.

Part of the reason 3.5” drives (and controllers) from this period are harder to find is this was the era of on-disk copy protection. The 3.5” drives never coped with it well, compared to 5 1/4" and was subsequently discouraged. Some developers ignored the fact 3.5" and on-disk copy protection DO NOT MIX well (usually companies like Autodesk and others, especially gov't contractors) and these can/do cause issues depending on how horribly aggressive the implementation is. If it's a one time check it may be fine, but that's the one and only exception to the rule with 3.5" on-disk. Not saying you can't go 3.5", but keep in mind overly protected on-disk copy protection can cause issues. Yes, it was nothing more than annoying and it does absolutely nothing; 1:1 disk copy programs which "blindly" copy these disks will bypass 90%+ of this nonsense (you need to mirror the "bad sectors" if it's based on a sector check) IF you need to backup these programs, unless you can maintain 2 concurrent working copies. "Nibbler" copiers work best as it does it as it sees the disk.
For more advanced methods, cracks are needed (either OG cracking group work, or modern archival group cracks work). Anything done recent-ish prior to upload is cracked by archival groups.
The reason I mention this is thanks to cracking groups it can **MOSTLY** be written off, but be leery of originals with intact copy protection. With how well the Apple II accommodates this junk (being predominately 5 1/4"), a lot of SW has it :(.

A clone of the 3.5” controller card can be found here. If you want an original Apple 3.5” card, expect to pay a lot more for it.