Scott, welcome to TFP!!
You don't need the special union (SP 1485B or SP 1480) to attach the filter to the pump. You
do want to have a union between them, though! If the pump you have has a top discharge all you need to do is build a pedestal for the filter so that it's high enough so that you can use a male adapter out of the pump and then 90* into the union and male adapter into the filter 8) Cinder blocks or paving stones , or a combination of the 2 should work well, just make sure that it's big enough to set the filter on and level.
It'd probably be a good idea to open the filter and check the fingers, lube the sealing gasket and the o-rings on the bump shaft. Also, be sure that the flapper check valve is in place (it's inside the in port on the bottom of the filter)!
Use another union on the effluent line (coming off the top of the filter).
I wrote a guide on use and care for DE filters
here - it's better to break the unit down and hose off the fingers than to just 'bump and dump' as that way you know you removed all the used DE and can just add the full 5 lbs of DE and not have to worry about over or under charging the filter.
Good luck with the new filter! If you need any more help with this, feel free to ask us any questions that come up :-D (the only dumb question is the one unasked

)