Will the Clip + work with this card?

Sandisk Ultra 64 GB micro sdxc uhs-1 card?

It’s on sale and I’d love to have a 64gb

If you reformat it to fat32 then yes. Your player will still only handle less then 6 or 7 thousand files though.

Is that hard to do?

Given the right software, a couple mouse clicks and a few minutes is all it takes.

Windows itself can be used to reformat the card–very easy to do.  

I may be wrong, but I think Windows will recognize it as SDXC and not give any options to format it any other way. There are other options though.