Color format not supported

OK this explanation is going to seem to be a bit bizarre but I have to start with the statement that Acrobat has no scanning capabilities whatsoever. What it does is rely upon other scanning software to do it's work. In the Mac case, it gets a tad worse because it relies up the Mac application: Image Capture to do the scanning. This is doubly bad because IC is the worst scanning software I've ever encountered. No, really, it is. I could go into the history of this whole situation but I do not want to take the time.

Let me add here that you cannot "set" the color format in IC and it's software is locking in a format that Acrobat doesn't seem to want to deal with. 

Because you have a scanner, it came with scanning software. Can you please try to scan with that and see if Acrobat is happy with that? I suggest you save the scan(s) to a folder in your desktop (that's what I do) and save them in the TIF format. Then, after the scan is complete, simply drag the scan onto the Acrobat icon in your Dock. It will ask if you want to save this as a PDF. At this moment in time I forget if you have to set it to auto OCR or if it does that by default. 

Let me know how it goes and if this works I have some other information that will help you in your scanning. Good luck!